* Add Sentence class, to get a better interface for i/o than io_parse
* Commit further sbd work in transitions
* Switch to sentence.pyx instead of io_parse. Still a fair bit to do, including updatting tagger.pyx
* Updating tagger for Sentence class
* Comment tagger functionality back in
* Restore orthographic features to sentence class
* Fix bug in normalize_word
* Fix POS file reading
* Fix CoNLL output
* Read in files in the new way
* Add sentence.pyx to setup.py
* Remove extra argument from parse_features
* Fix sentence loading
* Restore missing features, taken out when moving from io_parse
* Resolve big merge, from dirty branch where I was refactoring io_parse into sentence. Changes to transition also got caught up in it.
* Upd gitignore
* Merge small stash
* More mergery, plus implementation of can_shift etc validation functions
* Fix bugs in segmentation oracle.
* Bug fixes to oracle for segmentation.