fix and test #231 (code blocks are not shown for annotated features)

[Gleethos]

It looks like annotations cause the VividASTVisitor to ignore the blocks of a specification method. I fixed it by overriding the method doing the annotation visiting and skipping the traversal of the annotation code entirely...

My fix did not cause any regressions in the test suite and I also added an additional test in order to make sure that this bug does not come back some day...