Minor modification to OSX bundle-making script.

Chiefly, I decided to just fall in line and only use Frameworks where they are provided by the OS itself. Also, changed BUILD_TYPE from "Debug" to "RelWithDebInfo"
Fix window-height stepping.

This is not really visible to the user, but a stepping of "16" in height produced some very weird resolutions.
Add some stuff to .gitignore

Added OSX's "performous-app-build.sh" products to .gitignore.
Merge branch 'master' of https://github.com/performous/performous