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/AbandonedShip_Rooms_B1F/scripts.inc

@@ -7,7 +7,7 @@ AbandonedShip_Rooms_B1F_MapScript1_237FBD: @ 8237FBD
 	end
 
 AbandonedShip_Rooms_B1F_EventScript_237FC6:: @ 8237FC6
-	msgbox AbandonedShip_Rooms_B1F_Text_237FCF, 2
+	msgbox AbandonedShip_Rooms_B1F_Text_237FCF, MSGBOX_NPC
 	end
 
 AbandonedShip_Rooms_B1F_Text_237FCF: @ 8237FCF