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.
Now you can grep for it¹!
¹ Editor that's actually smart enough to not only correctly detect
Shift-JIS during grepping, but also match the characters in a search
regardless of file encoding, sold separately
Part of P0141, funded by [Anonymous] and rosenrose.
nmlgc