Merge pull request #6 from rgrinberg/master

Yo dawg, i heard you liked types...
Various cleanups

- Clean-up the typed representation of serializable JSON
- add int32/int64/triple combinators
- fix a bug with the option types
- fix the type of the `unit` combinator
Update CHANGES
Add @whitequark release scripts
Bump version
Merge pull request #7 from samoht/master

Various API cleanups
Fix release script