Renderer|Oculus Rift: Apply multisampling in unwarped frame buffer

This multisampling is intended to counter the 1.5x scaling. The
warping is smoothed out by using a linear filter on the color
texture. The end result: less jaggies.

Todo: Make configurable via a settings dialog.
Refactor|libgui|GLInfo: Better name for a method
Fixed|UI|Automap: Clipping of the automap when sidebar is open

The normalized coordinates should be agnostic of the game widget’s
size and position, so normalize against the widget instead of
the full view.