This commit introduces bopti for fxcg50 with the first basic 16-bit
formats. The performance is rather slow, especially for large images,
and will need refinements and/or overclock to be really efficient in
full-screen real-time applications.
This change finally introduces gray image rendering with bopti. This
is the final iteration of bopti v2 and certainly the fastest so far.
All four profiles are supported, without change to the format.