adds constants, cleans up callstd and msgbox code

* adds some constants for standard script names and messagebox types
* replaces some callstd calls with msgbox calls where equivalent
* replaces msgbox and callstd calls using raw digits with versions that use the constants

data/maps/SealedChamber_InnerRoom/scripts.inc

@@ -28,7 +28,7 @@ SealedChamber_InnerRoom_EventScript_2391F8:: @ 82391F8
 	waitstate
 	playse SE_DOOR
 	delay 40
-	msgbox gUnknown_0827301B, 4
+	msgbox gUnknown_0827301B, MSGBOX_DEFAULT
 	closemessage
 	fadeinbgm 0
 	setflag FLAG_0x0E4