Added 2in3 versioning and default is now the production version. Added submodules to make it possible to omit YUI3 metadata.

querystring-parse requires array-extras [fixes #2528621]. Updated widget and overlay metadata.

For testing: Loader moved out of seed into a separate module. Seed (yui-base,queue,get) will bootstrap loader if there are missing modules. Self healing without loader still works if the add() metadata is right.

loader reorg