These are used from quite a few places, so it seems best to just name
them after the rect on the playfield they leave out, which is then
typically where the background picture goes.
…*except* that in doing this, we quickly run up against the symbol
length limit of 32 characters. TASM can expand it via the /mv option,
but TCC only lets you *reduce* it to even less. (Why?)
So, my initial idea of `playfield_fill_around_(x)_(y)_(w)_(h)` wouldn't
have worked. But those coordinates are kinda important, I'd say…
Well then, let's just go with `fillm` instead of `fill_around` then.
"Fill with mask at the given coordinates"… yeah, that would work.
Part of P0029, funded by zorg.
nmlgc