A future sprite converter (documented in #8) could then convert these
to C or ASM arrays.
(Except for the piano sprites for TH05's Music Room, which are stored
and used in such a compressed way that it defeats the purpose of
storing them as bitmaps.
I tried `brge` for the latter, but that had *the* most horrible
ergonomics, and I misspelled it as `bgre` 100% of the times I typed it
manually. Turns out that `dots` is also consistent with master.lib's
naming scheme, leaving `planar` to *actually* refer to types storing
multiple planes worth of pixels. These types are showing up more and
more, and deserve something better than their previous long-winded and
misleading name.
Part of P0081, funded by Ember2528.