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_OuterRoom/scripts.inc

@@ -118,7 +118,7 @@ SealedChamber_OuterRoom_EventScript_2391D0:: @ 82391D0
 	end
 
 SealedChamber_OuterRoom_EventScript_2391E3:: @ 82391E3
-	msgbox gUnknown_0827304E, 4
+	msgbox gUnknown_0827304E, MSGBOX_DEFAULT
 	releaseall
 	end