Use labels instead of constants for HRAM

Use explicit ldh instruction to access HRAM locations, don't rely on optimizing ld

engine/menus/main_menu.asm

@@ -150,7 +150,7 @@ MainMenu_GetWhichMenu:
 	ret
 
 .next
-	ld a, [hCGB]
+	ldh a, [hCGB]
 	cp $1
 	ld a, $1
 	ret nz
@@ -217,7 +217,7 @@ MainMenu_PrintCurrentTimeAndDay:
 	and a
 	ret z
 	xor a
-	ld [hBGMapMode], a
+	ldh [hBGMapMode], a
 	call .PlaceBox
 	ld hl, wOptions
 	ld a, [hl]
@@ -227,7 +227,7 @@ MainMenu_PrintCurrentTimeAndDay:
 	pop af
 	ld [wOptions], a
 	ld a, $1
-	ld [hBGMapMode], a
+	ldh [hBGMapMode], a
 	ret
 
 .PlaceBox:
@@ -257,7 +257,7 @@ MainMenu_PrintCurrentTimeAndDay:
 	decoord 1, 15
 	call .PlaceCurrentDay
 	decoord 4, 16
-	ld a, [hHours]
+	ldh a, [hHours]
 	ld c, a
 	farcall PrintHour
 	ld [hl], ":"
@@ -313,7 +313,7 @@ MainMenu_PrintCurrentTimeAndDay:
 
 Function49ed0:
 	xor a
-	ld [hMapAnims], a
+	ldh [hMapAnims], a
 	call ClearTileMap
 	call LoadFontsExtra
 	call LoadStandardFont