Raspberry Pi 3 OpenGL support

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The openGL drivers in Raspbian have made a lot of progress, where now you can select a KMS mode driver which seems to be performing well. It isn't as fast as an i5, but it feels like a standard linux PC. Installation with the armhf .deb files is pretty straight forward, and clicking on a .love file on the desktop runs just like on a normal PC.

To test the Rpi I made a simple demo that draws dots on the screen and fades them out, and also rotates a swarm of 2000 dots in 3d. On an i5 it easily gets 60fps, on the RPi 3 it sits at about 43fps and the cpu load is 15%. Eric Anholt is still optimising the driver, so it will be interesting to see if that fps can get up closer to 60.