This should help make RGBDS portable to systems with 16-bit integers,
like DOS.
For kicks, use the macros for 16-bit and 8-bit integers.
Fix other miscellaneous things, like #include ordering and other
printf-format related things.
Reduce repitition in math.c while I'm there.
This avoids redundancy between them (and also having to port fixes and features)
The error messages have been preserved through a string reporting mechanism
Stop using that bitfield for everything, including what can be determined otherwise
It also makes it easier to have a sane state, since some bits were (supposedly)
mutually exclusive
POSIX leaves undefined the order of output if stderr is injected into stdout,
and in practice it differs on Windows (Linux buffers both streams separately,
Windows interleaves them as they arrive without buffering).
This should help testing on other platforms
