Added support for UUID-based player lookups in 1.7.5+

You could argue that ShadowRanger's conversion of everything to UUID is better, but that would result in us having to contact Mojang's servers simply to fetch a player by UUID for versions < 1.7.5. It seems excessive (not to mention that uncached contact can result in rate limiting) when the server itself will not remember who they are across name changes. If they can re-obtain everything in their inventory, they can re-run /ac.

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

@@ -39,4 +39,12 @@ public interface IPlayerDataManager {
      */
     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);
+
 }