the documentation for 'Iso' should use 'over' instead of 'set' .
Merge pull request #314 from nushio3/master

Fix documentation on Control.Lens.Iso
Added 'zlib' support

Since 'zlib' is in the platform, it seems only reasonable.
Merge branch 'topic/zlib-lens' of https://github.com/pthariensflame/lens into topic/zlib-lens