Unexpirable diseases & Holy Symbol patch

Fixed diseases becoming unexpirable after trying to change channels or entering the Cash Shop.
Fixed Holy Symbol acting oddly in solo scenario.
Adjusted Summon Sack lv. 9, that would try to spawn mobs with inexistent id on the field.

src/scripting/AbstractPlayerInteraction.java

@@ -177,6 +177,10 @@ public class AbstractPlayerInteraction {
 		return getPlayer().getEventInstance();
 	}
         
+        public MapleInventory getInventory(int type) {
+                return getPlayer().getInventory(MapleInventoryType.getByType((byte) type));
+        }
+        
         public MapleInventory getInventory(MapleInventoryType type) {
                 return getPlayer().getInventory(type);
         }

src/scripting/event/EventInstanceManager.java

@@ -425,6 +425,16 @@ public class EventInstanceManager {
                         rL.unlock();
                 }
 	}
+        
+        public MapleCharacter getPlayerById(int id) {
+                rL.lock();
+                try {
+                        return chars.get(id);
+                }
+                finally {
+                        rL.unlock();
+                }
+	}
 
 	public List<MapleCharacter> getPlayers() {
                 rL.lock();
@@ -1331,6 +1341,15 @@ public class EventInstanceManager {
                 }
         }
         
+        public final int gridSize() {
+                rL.lock();
+                try {
+                        return playerGrid.size();
+                } finally {
+                        rL.unlock();
+                }
+        }
+        
         public final void gridClear() {
                 wL.lock();
                 try {