Block the cabal-dev harder.

The cabal-dev simlink wasn't blocked by the gitignore, only a normal directory.
Fixes haskell-opengl/OpenGL#35.

The solution used is to cast it to GLint.
Adds a small note at TextureUnit about uniforms.
Merge pull request #36 from Laar/master

Hide cabal-dev simlink.
Merge pull request #37 from Laar/hopengl35

Fix issue #35.
Merge remote-tracking branch 'upstream/master'

* upstream/master:
  Adds a small note at TextureUnit about uniforms.
  Fixes haskell-opengl/OpenGL#35.
  Block the cabal-dev harder.