Log Message:
Update mecab to 0.996.

2013-02-18 MeCab 0.996
* fixes missing linkage with iconv.
* Add function to generate new CSV file from adding costs and left/right context
  ID of CVS for user's dictionary.
* Add Lattice::set_result() method for generated analysis result to Lattice
2013-01-24 MeCab 0.995
* Reimplementation of partial analysis function
* Add API for partial analysis function (Lattice:set_boundary_constrant,
  Lattice::set_feature_constranit)