Fix getOnlinePlayers call to support all versions

Moved IPlayerDataManager from api module to common module - it is not part of the API as there is no supported way to obtain an instance of it.

api/src/main/java/com/lishid/openinv/internal/IPlayerDataManager.java

@@ -1,50 +0,0 @@
-/*
- * Copyright (C) 2011-2014 lishid.  All rights reserved.
- * 
- * This program is free software: you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation,  version 3.
- * 
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- * 
- * You should have received a copy of the GNU General Public License
- * along with this program. If not, see <http://www.gnu.org/licenses/>.
- */
-
-package com.lishid.openinv.internal;
-
-import org.bukkit.OfflinePlayer;
-import org.bukkit.entity.Player;
-
-public interface IPlayerDataManager {
-
-    /**
-     * Loads a Player for an OfflinePlayer.
-     * </p>
-     * This method is potentially blocking, and should not be called on the main thread.
-     * 
-     * @param offline
-     * @return
-     */
-    public Player loadPlayer(OfflinePlayer offline);
-
-    /**
-     * Gets a unique identifying string for an OfflinePlayer.
-     * 
-     * @param player
-     * @return
-     */
-    public String getPlayerDataID(OfflinePlayer player);
-
-    /**
-     * Gets an OfflinePlayer by the given unique identifier.
-     * 
-     * @param identifier the unique identifier
-     * @return the OfflinePlayer, or null if no exact match was found
-     */
-    public OfflinePlayer getPlayerByID(String identifier);
-
-}