app.nlp.mention: a redesign of the parse-based mention finder

Conll alignment precision and recall before:

precision = 0.3720178302360623
recall = 0.7998785097192225
precision = 0.3260515919126191
recall = 0.8017142857142857

and after:

precision = 0.3902639222124006
recall = 0.8343682505399568
precision = 0.33014135886912904
recall = 0.8274285714285714