Overhauled uniform handling.

Closes #41
Refactored ModelManager to ModelWorld.
Implemented instancable camera.
Implemented ShaderProgramSet.
Initial efforts on implementing the render target.
Added a test which tests if there are enough tests.

Yes. I'm a genious.
Finished render system overhaul.

Closes #42
Merge branch 'feature/renderer-overhaul'