* Improve NER per type scoring
* include all gold labels in per type scoring, not only when recall > 0
* improve efficiency of per type scoring
* Create Scorer tests, initially with NER tests
* move regression test #3968 (per type NER scoring) to Scorer tests
* add new test for per type NER scoring with imperfect P/R/F and per
type P/R/F including a case where R == 0.0
