* Give special value for deleted words
* Increment state score from the move score directly, allowing the use of different figure of merits if necessary
* Change some debugging code
* Upd for new pathlib
* Fix major regression from incorrect has_child_in_buffer method
* Fix major regression from beam scoring calculation
* Move tag_word calls below a conditional, preventing them from interfering with non-lattice parsing
* Rearrange functions, for readability
* Change history to a vector, simplifying memory management
* Add beam_factor parameter, to prune beam by distance from top candidate, for variable width beam.
* Bug fix to count_feats: ensure we don't transition past the history when we haven't seen_diff yet.