These are used where the head or the feet of the player/enemy have to be
moved in an animation, and shouldn't overlap. These aren't actual GFX
and should be loaded with the proper commands, and they're always loaded
at the end of the VRAM area.
Furthermore, I've defined BATTLEANIM_BASE_TILE, which is the tile from
which battle animation graphics may start to load. This value was picked
to make sure at least an entire pokemon pic fits in the area before it,
even though it doesn't seem very used...
