MacroGroovy

Hi!

I would like to donate my MacroGroovy project to groovy-core. Since it shares code with AstBuilderTransformation, I decided to refactor existing code of it because I don't want to make duplicates. 


It's still in "work in progress"  state and i'm expecting comments and suggestions from you.
Sure so in fact all the tests in SimpleMacroTest should be rewritten in terms of their assertions?