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/DesertRuins/scripts.inc

@@ -51,7 +51,7 @@ DesertRuins_EventScript_22D9DB:: @ 822D9DB
 	end
 
 DesertRuins_EventScript_22D9EE:: @ 822D9EE
-	msgbox gUnknown_0827304E, 4
+	msgbox gUnknown_0827304E, MSGBOX_DEFAULT
 	releaseall
 	end