Make generator result caching framework api available publically.

Removes "Experimental" comment warnings.
Renames the class GeneratorExt to IncrementalGenerator.
Merges methods from GeneratorContextExt into GeneratorContext.
General refactoring and relocating of several support classes.
Added added support for versioning for incremental generators.

Review at http://gwt-code-reviews.appspot.com/1468804


git-svn-id: https://google-web-toolkit.googlecode.com/svn/trunk@10492 8db76d5a-ed1c-0410-87a9-c151d255dfc7
37 files changed