Whew, time to look at every `int` variable we ever declared! The best
moment to do this would have been a year ago, but well, better late
than never. No need to communicate that in comments anymore.
These shouldn't be used for widths, heights, or sprite-space
coordinates. Maybe we'll cover that another time, this commit is
already large enough.
Part of P0111, funded by [Anonymous] and Blue Bolt.
And immediately, we discover another two hardcoded sprites, with, of
course, another set of functions for blitting and unblitting them…
Part of P0099, funded by Ember2528.
nmlgc