AnswerTextMerger: Purely syntactic answer merging

This is just a proof-of-concept phase but should be already useful.
It's not clear how to best sum the scores, a decayed sum may be sensible
instead...
AnswerTextMerger: Remove a forgotten over-verbose debug print
answer SyntaxCanonization: Move answer syntax canon. from AnswerTextMerger to AnswerAnalysis

It is going to be useful for syntactic evidence diffusion as well, plus
maybe we can use it for the initial CAS merge as well.
Merge branch 'master' into f/ansmerge
AnswerTextMerger debug prints: Clearly mark the question texts
AnswerTextMerger: Merge answers in score-descending order

This simplifies best answer extraction and will make it easier to use
other score combination strategies than simple summing.
EvidenceDiffusion: New pipeline stage, similar to AnswerTextMerger but with substrings and without removals
AnswerTextMerger: Actually just merge the FVs instead of score transfer
AnswerScoreLogistic: Ignore unknown features
Merge branch 'f/ansmergefv' into f/evdiff

Conflicts:
	src/main/java/cz/brmlab/yodaqa/analysis/answer/AnswerFV.java
	src/main/typesystem/CandidateAnswerTypes_TS.xml
AnswerScoreLogistic: Update the model