A few graphics program for the Wii in order to test behavior of the GPU and
check if the emulator does it right.

Currently available:

* scissor: checks the scissor behavior with bad boxes (right < left, width =
  0), used to test

* zcomploc: checks the alpha/depth interaction (GX_SetZCompLoc)

* zfreeze: checks the Z freezing behavior (GX_SetCoPlanar)