Sped up sphere and light fragment shaders by moving matrix ops into vertex shaders
Managed OpenGL source reorganization
Made pict3ds untyped (though the engine is still typed)
Stubbed out snip class (read/write support in code files)
Useless wheel-spinning on snip reading/writing
Make pict3d work in Racket, Typed Racket, and HTDP languages

This was exceedingly painful. TR's contract generation for GUI classes
is terrible; it generally can't do it. Ended up hacking the types
directly into type environments. Probably will do the same with
functions for managed GL contexts.

HTDP's support for custom pretty printing is obscure, but it's there.
Pict3D instances don't show in the stepper, though. It probably has
something to do with TR's auto-generated contracts.