Upgrade to Xtext 2.5.
Merge branch 'refs/heads/feature/datasource' into develop
Refactored generator plugins.

Each platform generator plugin now registers its own org.eclipse.xtext.builder.IXtextBuilderParticipant - I believe this is much more in the spirit of Xtext.
Enabled generating output files to project root folders.
Changed output directories for iOS generator modules.
Merge branch 'refs/heads/feature/experimental/multiple_igenerators' into develop