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/OldaleTown_House1/scripts.inc

@@ -2,7 +2,7 @@ OldaleTown_House1_MapScripts:: @ 81FBE85
 	.byte 0
 
 OldaleTown_House1_EventScript_1FBE86:: @ 81FBE86
-	msgbox OldaleTown_House1_Text_1FBE8F, 2
+	msgbox OldaleTown_House1_Text_1FBE8F, MSGBOX_NPC
 	end
 
 OldaleTown_House1_Text_1FBE8F: @ 81FBE8F