Add more assert cases in the codebase (#1115)

* Add assert for FACING_GRASS_1 and FACING_GRASS_2

* Add more assert cases

* Add assert for HP bar colors

* Assert LINK_NULL == 0

* Fix assert syntax

* Add asserts for WILD_BATTLE == 1

* Add additional WILD assert

- I need to sleep more...

* Revert asserts for WILD_BATTLE and LINK_NULL

* Commit suggested changes

* Add more assert cases

* Fix syntax error

engine/battle/core.asm

@@ -624,7 +624,8 @@ ParsePlayerAction:
 	jr nz, .locked_in
 	xor a
 	ld [wMoveSelectionMenuType], a
-	inc a ; POUND
+	assert POUND == 1
+	inc a
 	ld [wFXAnimID], a
 	call MoveSelectionScreen
 	push af
@@ -3826,7 +3827,8 @@ TryToRunAwayFromBattle:
 	cp BATTLEACTION_FORFEIT
 	ld a, DRAW
 	jr z, .fled
-	dec a ; LOSE
+	assert DRAW - 1 == LOSE
+	dec a
 .fled
 	ld b, a
 	ld a, [wBattleResult]