Added datatype symbol

data/schema.cfg

@@ -1,6 +1,7 @@
 #textdomain wesnoth
 [schema]
     identifier="re ^[a-zA-Z0-9_ ]+$"
+    symbol="re ^[A-Z_]+$"
     string="re ^[ -~]+$"
     integer="re ^(\+|-)?[0-9]+$"
     float="re ^(\+|-)?[0-9]+(\.[0-9]*)?$"
@@ -85,9 +86,9 @@
         _about="repeated about-campaign"
 
         abbrev="required identifier translatable"
-        define="required identifier" #TODO: maybe require it to be uppercase?
+        define="required symbol"
         description="required string translatable"
-        difficulties="required string list"
+        difficulties="required symbol list"
         difficulty_descriptions="required string" #TODO: this one's especially complicated
         extra_defines="optional string list"
         first_scenario="required identifier"