motion_t is also used for certain animations in MAINE.EXE, so not all
instances refer to entities in playfield space. Explicitly specifying
the latter now allows us to gain…
Part of P0149, funded by Blue Bolt, Ember2528, and -Tom-.
Palette hacks not included yet. Yup, that's how all phases can use
hardware color #0 as their background color.
Completes P0147, funded by -Tom- and Ember2528.
nmlgc