Define ANIM_GFX for PLAYER and ENEMY

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...

constants/battle_anim_constants.asm

@@ -26,6 +26,9 @@
 	const BATTLEANIMSTRUCT_17
 BATTLEANIMSTRUCT_LENGTH EQU const_value
 
+; Start tile for battle animation graphics
+BATTLEANIM_BASE_TILE EQU 7 * 7  ; Maximum size of a pokemon picture
+
 ; BattleAnimObjects indexes (see data/battle_anims/objects.asm)
 	const_def
 	const ANIM_OBJ_00
@@ -804,6 +807,8 @@ BATTLEANIMSTRUCT_LENGTH EQU const_value
 	const ANIM_GFX_ANGELS
 	const ANIM_GFX_WAVE
 	const ANIM_GFX_AEROBLAST
+	const ANIM_GFX_PLAYER
+	const ANIM_GFX_ENEMY
 
 ; battle_bg_effect struct members (see macros/wram.asm)
 	const_def