Bring in DKPro, include tokit segmenter and opennlp postagger in QuestionAnalysis
QuestionAnalysis Segmenter: BreakIterator -> OpenNlp

Let's just be consistent, no other particular reason.
Revamp licencing terms: Dual-licence by ASLv2, GPLv3; rationale in LICENCE.md
QuestionAnalysis: Add some more advanced NLP processing

We do not use the extra annotations anywhere yet, that's to come next.

This also contains "results" (commented out code) of a little survey
of various engines available via DKPro.