Add headwork project stub
Add headword extraction and wordnet utils (over jwi) to nlptools.
- Declare HeadExtractor interface, rename UW implementation to UWHeadExtractor.
- UWHeadExtractor cleanup
- Add whWords and tag type tests to Postagger and PostaggedToken
UWHeadwordExtractor updates

- fix file name
- privatize internal methods
- misc cleanup
Merge branch 'headword' of https://github.com/gmjabs/nlptools into headword
Rename UWheadExtractor -> UWHeadExtractor