added annotation level to NgramModel constructor
added some experiments calling getTargetAnnotations() instead of getTargetPhrase()
added a new function getTargetPhraseOrAnnotations in PhrasePair.h which calls either getTargetPhrase() or getTargetAnnotations() depending on the annotation_level.
tidied up NgramModel and FeatureFunction. added annotation level to the logger in NgramModel
Fixed word penalty bug affecting certain platforms.
Disabled reference tracking on phrase and phrase pair flyweights.
Fixed flyweight serialisation templates.
Merge branch 'aaron' of https://github.com/chardmeier/docent into aaron