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.
Light and dark were erroneously swapped in my documentation's
formulae, but not in the way operands were cancelled when x=0,
leading to strange results.
* Now uses topti instead of fxlib for text (including MMU failure)
* Fit .pretext into 4k for everything before MMU succeeds
* A short version of sprintf() for dynamic messages
* Support a driver function, status(), to allow early driver debug
* Expose more useful platform information in <gint/mpu.h>
* Expose the first of a few CASIOWIN syscalls