ThreadTracker + Attempt on NPC Disappearing fix

Engineered the ThreadTracker: server-embedded deadlock auditing tool, which will print error messages in case of found deadlocks (also showing all in-use locks on the time of the issue).
Changed the player's id on DB now starting from 20mil, thus preventing players from overwriting NPC/mobs with same oid in-game. Requires proper testing to see if the issue has been cleared.

src/server/maps/MapleMapItem.java

@@ -24,8 +24,10 @@ import client.MapleCharacter;
 import client.MapleClient;
 import client.inventory.Item;
 import java.awt.Point;
-import java.util.concurrent.locks.ReentrantLock;
+import java.util.concurrent.locks.Lock;
+import tools.locks.MonitoredReentrantLock;
 import tools.MaplePacketCreator;
+import tools.locks.MonitoredEnums;
 
 public class MapleMapItem extends AbstractMapleMapObject {
 
@@ -35,7 +37,7 @@ public class MapleMapItem extends AbstractMapleMapObject {
     protected byte type;
     protected boolean pickedUp = false, playerDrop;
     protected long dropTime;
-    private ReentrantLock itemLock = new ReentrantLock();
+    private Lock itemLock = new MonitoredReentrantLock(MonitoredEnums.MAP_ITEM);
 
     public MapleMapItem(Item item, Point position, MapleMapObject dropper, MapleCharacter owner, byte type, boolean playerDrop) {
 	setPosition(position);