AmoriaPQ + ItemSort fix + revamped GMShop

Implemented AmoriaPQ. Fixed an issue with ItemIdSortHandler where empty
vectors given to the sorting module would cause an exception thrown,
wiping players inventory items. Thanks to Vcoc, revamped shop data for
GMShop (shop id 1337). Mount quest for explorers now uses event script.

src/scripting/event/EventInstanceManager.java

@@ -1084,6 +1084,17 @@ public class EventInstanceManager {
                 }
         }
         
+        public final void linkPortalToScript(int thisStage, String portalName, String scriptName, int thisMapId) {
+                giveEventPlayersStageReward(thisStage);
+                thisStage--;    //stages counts from ONE, scripts from ZERO
+            
+                MapleMap nextStage = getMapInstance(thisMapId);
+                MaplePortal portal = nextStage.getPortal(portalName);
+                if (portal != null) {
+                        portal.setScriptName(scriptName);
+                }
+        }
+        
         // registers a player status in an event
         public final void gridInsert(MapleCharacter chr, int newStatus) {
                 wL.lock();