maximum length in ccss
cleaned up reader functions and unified interface
added ClassDict object
make parameter obligatory in Corpus
memoize .tokens() method of Corpus
.tokens() method of Corpus now returns a tuple instead of a list
.annotation() method of Corpus now returns a tuple instead of a list
Corpus iterator now iterates over flat fragments in the corpus, instead
of the keys
shrank the string representation of Corpus
added annotation_exact and tokens_exact methods to Corpus
added .restrict() method to Corpus
changed FragmentType, FragmentToken, ClassID to flat namedtuples
changed Interval.__len__ to .length, since python casts __len__ output
to uint
added lexicon() function
added contains() method to Interval
moar tests
added pairwise_substring_completion
added sets functions
added boundaries
added group