Fix error in example for printing dates, clarify comments in general

Fix error in example for printing dates, clarify comments in general

BUG=
R=kevmoo@google.com

Committed: https://github.com/dart-lang/intl/commit/4b447813add9e085ec490d5c08f72cac7db8ec0b

[Alan Knight, 2015-07-10 21:35:51]

alanknight@google.com changed reviewers:
+ kevmoo@google.com

[Alan Knight, 2015-07-10 21:35:52]

Improve Intl comments.

See e.g. https://github.com/dart-lang/intl/issues/71 
https://github.com/dart-lang/intl/issues/70

where people were confused about skeleton usage and an example was incorrect.

[kevmoo, 2015-07-10 23:31:03]

Also: Are you going to update the version? At least to a -dev?

https://codereview.chromium.org/1232003005/diff/1/README.md
File README.md (right):

https://codereview.chromium.org/1232003005/diff/1/README.md#newcode45
README.md:45: var format = new DateFormat.yMd("ar");
consider using

```dart
void noNeedToIndent() {}
```

for code samples.

https://codereview.chromium.org/1232003005/diff/1/lib/src/intl/date_format.dart
File lib/src/intl/date_format.dart (right):

https://codereview.chromium.org/1232003005/diff/1/lib/src/intl/date_format.da...
lib/src/intl/date_format.dart:56: * skeleton to which it resolves. The supported
set of skeletons is as follows. For
long lines

[Alan Knight, 2015-07-11 00:07:35]

I'm not clear on the versioning conventions. I normally only update it when I'm
intending to push something to pub. Should we be updating it every time, even if
just changing comments?

Here, it's actually been bumped on a previous rev that I just haven't published
yet because I was unexpectedly away and forgot about.

https://codereview.chromium.org/1232003005/diff/1/README.md
File README.md (right):

https://codereview.chromium.org/1232003005/diff/1/README.md#newcode45
README.md:45: var format = new DateFormat.yMd("ar");
On 2015/07/10 23:31:03, kevmoo wrote:
> consider using
> 
> ```dart
> void noNeedToIndent() {}
> ```
> 
> for code samples. 

Done.

https://codereview.chromium.org/1232003005/diff/1/lib/src/intl/date_format.dart
File lib/src/intl/date_format.dart (right):

https://codereview.chromium.org/1232003005/diff/1/lib/src/intl/date_format.da...
lib/src/intl/date_format.dart:56: * skeleton to which it resolves. The supported
set of skeletons is as follows. For
On 2015/07/10 23:31:03, kevmoo wrote:
> long lines

Done.

[kevmoo, 2015-07-11 00:08:31]

Basically, it should ALWAYS be -dev except for the commit you actually deploy.

Not a huge deal. Ask nweiz@ about it

LGTM

[Alan Knight, 2015-07-11 00:12:57]

Committed patchset #2 (id:20001) manually as
4b447813add9e085ec490d5c08f72cac7db8ec0b (presubmit successful).