python 3 support: long, dict.iterkeys(), itervalues(), iteritems()
pattern.vector: optimize chngrams()
pattern.vector: various improvements

- chunk() mix() and bin() helper functions
- Model.posterior_probability()
- Model.chi_squared()
- fsel() feature selection
- SVM.load() uses NamedTemporaryFile and now works on a server
pattern.metrics small fixes (nothing important)
pattern.text decamel(), lazyset
pattern.web: improved timeout errors, DOM CSS selectors bug fix
pattern.text.tree: token description can contain POS or (new) "pos"
pattern.server: better error handling
pattern.db: Datasheet.save() and load() have an optional "password" parameter (encryption)
pattern.nl: small lexicon update
update unit tests