Added hat effect packet and script support

doc/script_commands.txt

@@ -9161,5 +9161,15 @@ solution rather than sending the map and the monster_id.
 
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+*itemeffect(<State>,<Hat Effect ID>{, Hat Effect ID2, ... });
+
+This will set a Hat Effect onto the player. The state field allows you to
+enable (true) or disable (false) the effect on the player.
+The Hat Effect constants can be found in db/const.txt starting with HAT_EF_*.
+
+Requires client 2015-05-13aRagEXE or newer. 
+
+---------------------------------------
+
 Whew.
 That's about all of them.