Blender Git Loki

Decklink: use floating point texture format when possible.

Previous implementation was using GL_RED_INTEGER texture format for
all non-RGBA pixel format. This isn't supported by intel GPU (although
the GL_texture_rg extension is declared supported).
Floating RGBA texture are now used for the following pixel formats:
8BitYUV: Cb->B, Y0->G, Cr->R, Y1->A
10BitYUV: no fixed mapping between CbCrY and RGB, a shader is required
8BitARGB: direct mapping
8BitBGRA: direct mapping
10BitRGBXLE: direct mapping (A is undefined)
Other pixel formats are mapped to GL_RED_INTEGER (GL_R32UI internal
format, usampler2D must be used in the shader).
Note: the 10BitYUV, 10BitRGBXLE and 8BitARGB mapping only works on little-
endian host CPU. For big endian CPU, other formats must be used (not yet
implemented).

The texture MIN/MAX_FILTER is now set to NEAREST. Previously it was set to
LINEAR, which was detremental on multibytes pixel format.

The sample shader in the documentation for the above formats will be
changed to reflect the new mapping.