Evaluation of morphology & grammatical functions

- Add options for morphology & grammatical functions to corpus reader,
  enables evaluation and treebank transformations.
- Correctly use unknown word handling when --rerun option is passed to
  runexp.
- Rename 'unfold' to 'transformations', allowing specification of an
  arbitrary sequence of available transformations.
Keep state while iterating over set bits

Theoretically this should give a performance boost,
initial benchmarks indicate the difference to be negligible.