fully remove fboinsgrenderer, huge performance win here

before:
https://i.imgur.com/xeXNE0u.png

aka using the "game scene is a texture node that QQ renders on its own"

after: https://i.imgur.com/O5ILgeR.png

by rendering directly with beforerendering.

on this mesa 10.2.5, that is a huge difference (48fps -> 60fps), huge
buffer wait time decrease...and other things, like -7mb or so of vram
(on this 1366x768 laptop). hw is amd 4250 HD (old and crappy, but 3.3
capable).