Hired Merchant & Player shop fixes + Owl of Minerva

Thanks to BenjixD DietStory's dev team, many bugs found by them have
been patched (pirate quests, missing drop data, fly command, etc).
Implemented Owl of Minerva. Fixed many issues with Hired Merchant and
Player Shops. Fixed an error with the slot checking system. Added Wish
Tickets (circa-2006 GMS event) to be dropped on AmoriaPQ.

src/net/server/Server.java

@@ -71,6 +71,7 @@ import java.util.Calendar;
 import server.quest.MapleQuest;
 
 public class Server implements Runnable {
+    private static final Set<Integer> activeFly = new HashSet<>();
     private static final Map<Integer, Integer> couponRates = new LinkedHashMap<>();
     private static final List<Integer> activeCoupons = new LinkedList<>();
     
@@ -699,6 +700,18 @@ public class Server implements Runnable {
         return false;
     }
     
+    public void changeFly(Integer accountid, boolean canFly) {
+        if(canFly) {
+            activeFly.add(accountid);
+        } else {
+            activeFly.remove(accountid);
+        }
+    }
+    
+    public boolean canFly(Integer accountid) {
+        return activeFly.contains(accountid);
+    }
+    
     public World getWorld(int id) {
         return worlds.get(id);
     }