Remove synutils.h
Move non-MaxEnt code out of utils

1. alignment.h, argument_reorder_model.h, src_sentence.h, tree.h,
   tsuruoka_maxent.h -> decoder/ff_const_reorder_common.h.

2. Trainers source files (argument_reorder_model.cc and
   constituent_reorder_model.cc) are moved to training/const_reorder.
Remove SBitArray and use vector<bool> instead
Remove index mapping
Remove unused field in TargetTranslation
Use hashed state contents as rescoring state
Consider const_reorder state when rescoring