We've been establishing `screen` as meaning "a coordinate rooted at the
top-left corner of the display", whereas most of the Subpixels in >TH01
are rooted at the top-left of the playfield.
Part of P0112, funded by [Anonymous] and Blue Bolt.
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.
With all the memmove()-style shifting of individual lines, there's
probably a point to reserving 20 lines per set, but only ever rendering
4 of them. We'll see once I get to decompile all of these functions.
Part of P0110, funded by [Anonymous] and Blue Bolt.
Not just used for the zooming lines in Shinki's background, but also
for the pentagram (and circle!) in EX-Alice's background.
Part of P0110, funded by [Anonymous] and Blue Bolt.