OK, this is the big one. We still keep using `#include` guards only
where we absolutely need to, but with each header now being valid in
isolation, this can now actually help *minimize* the length of each
translation unit's `#include` list. Turns out that after removing all
the duplicates, we only *actually* need to guard 29 headers across all
5 games.
Part of P0285, funded by [Anonymous] and iruleatgames.
Turns out the inlining behavior of `const` variables at global scope
that we've been relying on lately is actually exclusive to C++ mode…
once again!
Part of P0133, funded by [Anonymous].
The TH04 one might have the same function structure, but the only thing
that's actually identical in both games is the picture darkening loop.
Part of P0119, funded by [Anonymous] and -Tom-.
The pascal calling convention for TH03's input mode functions actually
sort of matters, since we have this nice function pointer type that
expects pascal.
nmlgc