Blender Git Loki

Updated gpu.types.GPUOffscreen.py example file

The image I get is a bit too dark, which is the same I get in the viewport
itself when there is no Display Device. So I believe for cases like this
we need to have color management on top of the buffer.

Also, on EEVEE it looks like it needs to clear some extra buffers. You can see
that, by rotating the camera view around.

That said, this is the first step to bring back fun addons
that use external offscreen buffers.

Note: When using gpu offscreen with POST_VIEW (as oppose to POST_PIXEL)
I get a crash with DST having 0xFF..