A CRT shader that handles interlaced video.

A CRT shader that handles interlaced video.

This is a slight modification of shaders/OpenGL/v1.0/CRT.shader that
detects when it's being fed an interlaced video frame, and only displays
the odd or even fields as appropriate. This provides more authentic and
natural rendering of interlaced frames, but requires features from the
v1.1 spec so it can't just replace the original CRT shader.

The original modification was done by cgwg here:

    http://board.byuu.org/viewtopic.php?p=41966#p41966

...and rebased onto the latest version of the CRT shader by hunterk:

    http://board.byuu.org/viewtopic.php?p=47087#p47087