Made the binding resolution on Rascal JDT AstNode optional :

- small performance and memory usage gain for JDT::extractClass:
	AstNode@javaType has been removed as AstNode@bindings["typeBinding"]
duplicates it ( backward incompatible :-) )

- significant performance gain for JDT::createAstFromFile: due to
parser.setResolveBindings(false);