Gradually fades a part of the palette between two others.
Gradually fades a part of the palette from the source palette to the dest
palette. The speed is from 1 (the slowest) up to 64 (instantaneous). This
routine only affects colors between from and to (inclusive: pass 0 and
255 to fade the entire palette).
Note that this function will block your game while the fade is in effect,
and it won't work right visually if you are not in an 8 bit color depth
The following projects include source code containing this keyword: