Fix #709 miscellaneous issues

engine/events/odd_egg.asm

@@ -23,13 +23,13 @@ _GiveOddEgg:
 .not_done
 
 	; Break when [hRandom] <= de.
-	ldh a, [hRandom + 1]
+	ldh a, [hRandomSub]
 	cp d
 	jr c, .done
 	jr z, .ok
 	jr .next
 .ok
-	ldh a, [hRandom + 0]
+	ldh a, [hRandomAdd]
 	cp e
 	jr c, .done
 	jr z, .done

engine/link/mystery_gift.asm

@@ -985,7 +985,7 @@ Function104faf:
 	cpl
 	ld b, a
 	xor a
-	ldh [hMGJoypadPressed + 2], a
+	ldh [hMGPrevTIMA], a
 	call Function104d86
 .asm_104fd2
 	inc b
@@ -1008,10 +1008,10 @@ Function104faf:
 	bit 1, a
 	jr nz, .asm_104fe5
 .asm_104fed
-	ldh a, [hMGJoypadPressed + 2]
+	ldh a, [hMGPrevTIMA]
 	ld d, a
 	ldh a, [rTIMA]
-	ldh [hMGJoypadPressed + 2], a
+	ldh [hMGPrevTIMA], a
 	sub d
 	cp $12
 	jr c, .asm_104ffd

engine/overworld/events.asm

@@ -813,7 +813,7 @@ PlayerMovement:
 CheckMenuOW:
 	xor a
 	ldh [hMenuReturn], a
-	ldh [hMenuReturn + 1], a
+	ldh [hUnusedFFA1], a
 	ldh a, [hJoyPressed]
 
 	bit SELECT_F, a

engine/overworld/player_object.asm

@@ -20,10 +20,10 @@ SpawnPlayer:
 	ld a, -1
 	ld [wObjectFollow_Leader], a
 	ld [wObjectFollow_Follower], a
-	ld a, $0
+	ld a, PLAYER
 	ld hl, PlayerObjectTemplate
 	call CopyPlayerObjectTemplate
-	ld b, $0
+	ld b, PLAYER
 	call PlayerSpawn_ConvertCoords
 	ld a, PLAYER_OBJECT
 	call GetMapObject