Large update. Details below, but main change is moved planet rendering to its own file

- GLWidget has concept of Planet object, that know how to render and make itself
- Cursor hidden since it's not needed
- Disabled GLM_FORCE_RADIANS for Mac only
- Fixed a few minor warnings from shaders
- Setup double buffering but maybe not useful?
- Seed actually taken into account in noise shader
- Refresh doesn't refresh the shaders too since that's not needed