Experimental DB pool + fixed stat overflow on equips

Implemented EXPERIMENTAL DBCP (connection pool), trying to improve
concorrent access to DB. Added door portals on Kerning Square. Fixed
equipments getting stat overflow when upgrading stats. Fixed expiring
pets crashing the client in some cases.

src/client/MonsterBook.java

@@ -91,7 +91,8 @@ public final class MonsterBook {
     }
 
     public void loadCards(final int charid) throws SQLException {
-        try (PreparedStatement ps = DatabaseConnection.getConnection().prepareStatement("SELECT cardid, level FROM monsterbook WHERE charid = ? ORDER BY cardid ASC")) {
+        Connection con = DatabaseConnection.getConnection();
+        try (PreparedStatement ps = con.prepareStatement("SELECT cardid, level FROM monsterbook WHERE charid = ? ORDER BY cardid ASC")) {
             ps.setInt(1, charid);
             try (ResultSet rs = ps.executeQuery()) {
                 int cardid, level;
@@ -107,6 +108,8 @@ public final class MonsterBook {
                 }
             }
         }
+        
+        con.close();
         calculateLevel();
     }
 
@@ -139,6 +142,7 @@ public final class MonsterBook {
             ps = con.prepareStatement(query.toString());
             ps.execute();
             ps.close();
+            con.close();
         } catch (SQLException e) {
             e.printStackTrace();
         }