Moved Persist TC stuff around
ENTRY_KEYS is now Set
Refactor serialization in TSVs
nil
Added a bunch of backend engines for TSV persistence: CDB, LevelDB, plus Kyotocabinet and LMDB before. Tokyocabinet still seems like the best
Several changes in Annotation::Index and other small things
Do not bother to remove TSV::ENTRY_KEYS in BDB#range
nil
nil
nil
Version bump to 5.6.0
Regenerate gemspec for version 5.6.0