added plugin transformer which initializers can extend to do additional post-processing during tran…

CHANGELOG.md

+## 0.3.1-dev
+
+* Added `InitializePluginTransformer` class in `plugin_transformer.dart` which
+provides a base transformer class which can be extended to perform custom
+transformations for annotations. These transformers should be included after the
+main `initialize` transformer and work by parsing the bootstrap file so the
+program doesn't need to be re-analyzed.
+
 ## 0.3.0
 
 * Library initializers now pass a `LibraryIdentifier` to `initialize` instead of
 just a `Symbol`. This provides the package and path to the library in addition
 to the symbol so that paths can be normalized.
 
 ## 0.2.0
 
 * `entryPoint` and `newEntryPoint` transformer options were renamed to
 `entry_point` and `new_entry_pont`.
 
 * Added `html_entry_point` option to the transformer. This will search that file
 for any script tag whose src is `entry_point` and rewrite it to point at the
 bootstrapped file `new_entry_point`.
 
 * Top level properties and static class properties are now supported in
 initializer constructors, as well as List and Map literals,
 [5](https://github.com/dart-lang/initialize/issues/5).
 
 
 ## 0.1.0+1
 
 Quick fix for the transformer on windows.
 
 ## 0.1.0
 
 Initial beta release. There is one notable missing feature in the release
 regarding constructor arguments, see
 [5](https://github.com/dart-lang/initialize/issues/5).