Added getters to AST. Removed Production::__call. Added visitor support to AST. (guilherme: dont shoot me yet :-). visitor support doesnt hurt even if we do not use it for SQL generation). Lots of other things.

refactorings, a bug fix (#786) and improved performance for the hydration of results from polymorphic queries.

added tests for Collection. also fixed a bug with serialization in collections. added copyright header to the two new testfiles

Added tests for Doctrine_Access. It uses annotations for exceptions and to mark functions as tests. Also changed some logic in access and implementing classes to make the abstraction a little bit more solid

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