glir: WIP on ripping gloo in two. Buffer implemented.

Buffer class is implemente via glir. Still need to simplify the
buffer class by removing local storage.
gloo: remove local storage from buffer
style and py2 syntax
gloo: address reviewer comments
glir: simple fix
glir: gloo buffer tests pass again
gloo: fix setting of _nbytes and _size, plus minor fixes
glir: restore GLObject.target for now
Fixing some issues; hopefully tests can pass again
glir: try fix errors
GLIR: gloo.Program now makes use of GLIR
GLIR: fix tests for gloo.program
GLIR: texture uses GLIR

But need a bit of cleanup etc.
Texture cleanup
flake
GLIR: implement FBO in GLIR. Needs cleanup
cleaning up
GLIR: refactor commands a bit
GLIR: add some comments
Made GL functions in gloo use GLIR. Made examples work.

Need to figure out when to parse commands. Maybe app
should do it in on_paint.