WIP: use eglstreams of hybrid systems
I had a little free time thursday, so I thought I'd try to knock out the 3-big-monitors-on-hybrid-nvidia-machines issue (#205), but it ended up consuming most of thursday, friday, monday, and tuesday and I'm still not done
it works, but the branch needs quite a bit of clean up and there's bad performance, in part from
glReadPixels not being able to use the memcpy fast path. One thing that might be worth experimenting with is texturing straight from the mapped intel buffer object, that way we avoid the read pixels entirely.