@neobrain, could you confirm that this is correct?

It's been tested with various different games and fixes different textures, including in Animal Crossing, Kirby Triple Deluxe, and SMB3D.

Also adds better documentation and removes the one-off reimplementation
of the function in pica.h.

Fixes some games crashing.

This fixes the horizontal lines in Picross E, Cubic Ninja, Cave Story 3D and possibly others

- Centralizes color format encode/decode functions.
- Fixes endianness issues.
- Implements remaining framebuffer formats in the debugger.

This allows Virtual Console games to display properly.

Not really sure where the difference is, but some applications seem to use this 1:1 the same way...

Pica/TextureEnvironment: Add support for the MAD-like texture combiners and clean up texture environment logic.

Execute the division-by-W for perspective-correct interpolation of
values in the clipper, moving them out of the rasterization inner loop.