This is based on a port of kprint, which supports standard formats and
options, except for:
* Large parameters (ll)
* Floating-point types (%e, %E, %f, %F, %g, %G, %a, %A)
* 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