OpenGL Keplerian bodies

[BruceJohnJennerLawso]

Right now planets are rendered using a big circle cropped from a google images search. This looks awful in many cases, as well as not accurately showing where the surface is in map view, since its pretty much impossible to crop a big image in paint.net perfectly like this.

The solution for this would probably be to figure out how to render simple spheres using OpenGL, and from now on planets simply recieve their surface map in a normal format, ie, something like this

and then the OpenGL implementation simply uses that texture to set up the textured sphere and draw it onscreen as it sees fit based on zoom and things like that.

(I think this would be reasonable as a core Feb14 issue)