Pull args, intl, logging, shelf, and source_maps out of the SDK.

pkg/intl/README.md

-Intl
-====
-
-This package provides internationalization and localization facilities,
-including message translation, plurals and genders, date/number formatting
-and parsing, and bidirectional text.
-
-## General
-The most important library is [intl][intl_lib]. It defines the [Intl][Intl]
-class, with the default locale and methods for accessing most of the
-internationalization mechanisms. This library also defines the
-[DateFormat][DateFormat], [NumberFormat][NumberFormat], and
-[BidiFormatter][BidiFormatter] classes.
-
-## Current locale
-
-The package has a single current locale, called [defaultLocale][defaultLocale].
-Operations will use that locale unless told to do otherwise.
-
-To set the global locale, you can explicitly set it, e.g.
-
-      Intl.defaultLocale = 'pt_BR';
-
-or get it from the browser by
-
-      import "package:intl/intl_browser.dart";
-      ...
-      findSystemLocale().then(runTheRestOfMyProgram);
-
-To temporarily override the current locale, pass the operation
-to [withLocale][withLocale].
-
-      Intl.withLocale('fr', () => print(myLocalizedMessage());
-
-To override it for a very specific operation you can create a format object in
-a specific locale, or pass in the locale as a parameter to methods.
-
-      var format = new DateFormat.yMd("ar");
-      var dateString = format.format(new DateTime.now());
-      print(myMessage(dateString, locale: 'ar');
-
-## Initialization
-
-All the different types of locale data require an async initialization step
-to make
-sure the data is available. This reduces the size of the application by only
-loading the
-data that is actually required.
-
-Each different area of internationalization (messages, dates, numbers) requires
-a separate initialization process. That way, if the application only needs to
-format dates, it doesn't need to take the time or space to load up messages,
-numbers, or other things it may not need.
-
-With messages, there is also a need to import a file that won't exist until
-the code generation step has been run. This can be awkward, but can be worked
-around by creating a stub `messages_all.dart` file, running an empty translation
-step, or commenting out the import until translations are available.
-See "Extracting and Using Translated Messages"
-
-## Messages
-
-Messages to be localized are written as functions that return the result of
-an [Intl.message][Intl.message] call.
-
-      String continueMessage() => Intl.message(
-          "Hit any key to continue",
-          name: "continueMessage",
-          args: [],
-          desc: "Explains that we will not proceed further until "
-              "the user presses a key");
-      print(continueMessage());
-
-This provides, in addition to the basic message string, a name, a
-description for translators, the arguments used in the message, and
-examples. The `name` and `args` parameters are required, and must
-match the name and arguments list of the function.  In the future we
-hope to have these provided automatically.
-
-This can be run in the program before any translation has been done,
-and will just return the message string. It can also be extracted to a
-file and then be made to return a translated version without modifying
-the original program. See "Extracting Messages" below for more
-details.
-
-The purpose of wrapping the message in a function is to allow it to
-have parameters which can be used in the result. The message string is
-allowed to use a restricted form of Dart string interpolation, where
-only the function's parameters can be used, and only in simple
-expressions. Local variables cannot be used, and neither can
-expressions with curly braces. Only the message string can have
-interpolation. The name, desc, args, and examples must be literals and
-not contain interpolations. Only the args parameter can refer to
-variables, and it should list exactly the function parameters. If you
-are passing numbers or dates and you want them formatted, you must do
-the formatting outside the function and pass the formatted string into
-the message.
-
-      greetingMessage(name) => Intl.message(
-          "Hello $name!",
-          name: "greetingMessage",
-          args: [name],
-          desc: "Greet the user as they first open the application",
-          examples: {'name': "Emily"});
-      print(greetingMessage('Dan'));
-
-There is one special class of complex expressions allowed in the
-message string, for plurals and genders.
-
-      remainingEmailsMessage(int howMany, String userName) => 
-        Intl.message(
-          "${Intl.plural(howMany,
-              zero: 'There are no emails left for $userName.',
-              one: 'There is one email left for $userName.',
-              other: 'There are $howMany emails left for $userName.')}",
-        name: "remainingEmailsMessage",
-        args: [howMany, userName],
-        desc: "How many emails remain after archiving.",
-        examples: {'number': 42, 'userName': 'Fred'});
-
-      print(remainingEmailsMessage(1, "Fred"));
-
-However, since the typical usage for a plural or gender is for it to
-be at the top-level, we can also omit the [Intl.message][Intl.message] call and
-provide its parameters to the [Intl.plural][Intl.plural] call instead.
-
-      remainingEmailsMessage(int howMany, String userName) => 
-        Intl.plural(
-          howMany,
-          zero: 'There are no emails left for $userName.',
-          one: 'There is one email left for $userName.',
-          other: 'There are $howMany emails left for $userName.'),
-          name: "remainingEmailsMessage",
-          args: [howMany, userName],
-          desc: "How many emails remain after archiving.",
-          examples: {'number': 42, 'userName': 'Fred'});
-
-Similarly, there is an [Intl.gender][Intl.gender] message, and plurals
-and genders can be nested.
-
-      notOnlineMessage(String userName, String userGender) => 
-        Intl.gender(
-          userGender,
-          male: '$userName is unavailable because he is not online.',
-          female: '$userName is unavailable because she is not online.',
-          other: '$userName is unavailable because they are not online'),
-          name: "notOnlineMessage",
-          args: [userName, userGender],
-          desc: "The user is not available to hangout.",
-          examples: {{'userGender': 'male', 'userName': 'Fred'},
-              {'userGender': 'female', 'userName' : 'Alice'}});
-
-It's recommended to use complete sentences in the sub-messages to keep
-the structure as simple as possible for the translators.
-
-## Extracting And Using Translated Messages
-
-When your program contains messages that need translation, these must
-be extracted from the program source, sent to human translators, and the
-results need to be incorporated. 
-
-To extract messages, run the `extract_to_arb.dart` program.
-
-      pub run intl:extract_to_arb --output-dir=target/directory
-          my_program.dart more_of_my_program.dart
-
-This will produce a file `intl_messages.arb` with the messages from
-all of these programs. an [ARB]
-(https://code.google.com/p/arb/wiki/ApplicationResourceBundleSpecification)
-format file which can be used for input to translation tools like
-[Google Translator Toolkit](https://translate.google.com/toolkit/) 
-The resulting translations can be used to generate a set of libraries
-using the `generate_from_arb.dart` program.
-
-This expects to receive a series of files, one per
-locale. 
-
-      pub run intl:generate_from_arb --generated_file_prefix=<prefix> 
-          <my_dart_files> <translated_ARB_files>
-
-This will generate Dart libraries, one per locale, which contain the
-translated versions. Your Dart libraries can import the primary file,
-named `<prefix>messages_all.dart`, and then call the initialization
-for a specific locale. Once that's done, any
-[Intl.message][Intl.message] calls made in the context of that locale
-will automatically print the translated version instead of the
-original.
-
-      import "my_prefix_messages_all.dart";
-      ...
-      initializeMessages("dk").then(printSomeMessages);
-
-Once the future returned from the initialization call returns, the
-message data is available.
-
-## Number Formatting and Parsing
-
-To format a number, create a NumberFormat instance.
-
-      var f = new NumberFormat("###.0#", "en_US");
-      print(f.format(12.345));
-        ==> 12.34
-
-The locale parameter is optional. If omitted, then it will use the
-current locale. The format string is as described in
-[NumberFormat][NumberFormat]
-
-It's also possible to access the number symbol data for the current
-locale, which provides information as to the various separator
-characters, patterns, and other information used for formatting, as
-
-      f.symbols
-
-Current known limitations are that the currency format will only print
-the name of the currency, and does not support currency symbols, and
-that the scientific format does not really agree with scientific
-notation. Number parsing is not yet implemented.
-
-Note that before doing any number formatting for a particular locale
-you must load the appropriate data by calling
-
-      import 'package:intl/number_symbols_data_local.dart';
-      ...
-      initializeNumberFormatting(localeName, null).then(formatNumbers);
-
-Once the future returned from the initialization call returns, the
-formatting data is available. Note that right now this includes all
-the data for a locales. We expect to make this use deferred loading to
-reduce code size.
-
-## Date Formatting and Parsing
-
-To format a [DateTime][DateTime], create a [DateFormat][DateFormat]
-instance. These can be created using a set of commonly used skeletons
-taken from ICU/CLDR or using an explicit pattern. For details on the
-supported skeletons and patterns see [DateFormat][DateFormat].
-
-      new DateFormat.yMMMMEEEEd().format(aDateTime);
-        ==> 'Wednesday, January 10, 2012'
-      new DateFormat("EEEEE", "en_US").format(aDateTime);
-        ==> 'Wednesday'
-      new DateFormat("EEEEE", "ln").format(aDateTime);
-        ==> 'mokɔlɔ mwa mísáto'
-
-You can also parse dates using the same skeletons or patterns.
-
-        new DateFormat.yMd("en_US").parse("1/10/2012");
-        new DateFormat("Hms", "en_US").parse('14:23:01');
-
-Skeletons can be combined, the main use being to print a full date and
-time, e.g.
-
-        new DateFormat.yMEd().add_jms().format(new DateTime.now());
-          ==> 'Thu, 5/23/2013 10:21:47 AM'
-
-Known limitations: Time zones are not yet supported. Dart
-[DateTime][DateTime] objects don't have a time zone, so are either
-local or UTC. Formatting and parsing Durations is not yet implemented.
-
-Note that before doing any DateTime formatting for a particular
-locale, you must load the appropriate data by calling.
-
-        import 'package:intl/date_symbol_data_local.dart';
-        ...
-        initializeDateFormatting("de_DE", null).then(formatDates);
-
-Once the future returned from the initialization call returns, the
-formatting data is available.
-
-There are other mechanisms for loading the date formatting data
-implemented, but we expect to deprecate those in favor of having the
-data in a library as in the above, and using deferred loading to only
-load the portions that are needed. For the time being, this will
-include all of the data, which will increase code size.
-
-## Bidirectional Text
-
-The class [BidiFormatter][BidiFormatter] provides utilities for
-working with Bidirectional text. We can wrap the string with unicode
-directional indicator characters or with an HTML span to indicate
-direction. The direction can be specified with the
-[RTL][BidiFormatter.RTL] and [LTR][BidiFormatter.LTR] constructors, or
-detected from the text.
-
-        new BidiFormatter.RTL().wrapWithUnicode('xyz');
-        new BidiFormatter.RTL().wrapWithSpan('xyz');
-
-[intl_lib]: https://api.dartlang.org/apidocs/channels/stable/dartdoc-viewer/intl/intl
-[Intl]: https://api.dartlang.org/apidocs/channels/stable/dartdoc-viewer/intl
-[DateFormat]: https://api.dartlang.org/apidocs/channels/stable/dartdoc-viewer/intl/intl.DateFormat
-[NumberFormat]: https://api.dartlang.org/apidocs/channels/stable/dartdoc-viewer/intl/intl.NumberFormat
-[withLocale]: https://api.dartlang.org/apidocs/channels/stable/dartdoc-viewer/intl/intl.Intl#id_withLocale
-[defaultLocale]: https://api.dartlang.org/apidocs/channels/stable/dartdoc-viewer/intl/intl.Intl#id_defaultLocale
-[Intl.message]: https://api.dartlang.org/apidocs/channels/stable/dartdoc-viewer/intl/intl.Intl#id_message
-[Intl.plural]: https://api.dartlang.org/apidocs/channels/stable/dartdoc-viewer/intl/intl.Intl#id_plural
-[Intl.gender]: https://api.dartlang.org/apidocs/channels/stable/dartdoc-viewer/intl/intl.Intl#id_gender
-[DateTime]: https://api.dartlang.org/apidocs/channels/stable/dartdoc-viewer/dart:core.DateTime
-[BidiFormatter]: https://api.dartlang.org/apidocs/channels/stable/dartdoc-viewer/intl/intl.BidiFormatter
-[BidiFormatter.RTL]: https://api.dartlang.org/apidocs/channels/stable/dartdoc-viewer/intl/intl.BidiFormatter#id_BidiFormatter-RTL
-[BidiFormatter.LTR]: https://api.dartlang.org/apidocs/channels/stable/dartdoc-viewer/intl/intl.BidiFormatter#id_BidiFormatter-LTR