Add 0.9.5 changelog.

Merge pull request #135 from tmcgilchrist/v0.9.4

Document changes for 0.9.4 release.

Add 0.9.3 changes.

Merge pull request #120 from tmcgilchrist/topic/either

Bump upper bound of either.

Merge pull request #119 from helium/topic/stack

Bump upper bound on tasty-quickcheck

Merge pull request #117 from tmcgilchrist/topic/version-0.9.0

Version 0.9.0.