Revert adminmenu API changes.

plugins/include/adminmenu.inc

@@ -65,7 +65,7 @@
  * @param topmenu		Handle to the admin menu's TopMenu.
  * @noreturn
  */
-forward OnAdminMenuCreated(TopMenu topmenu);
+forward OnAdminMenuCreated(Handle topmenu);
 
 /**
  * Called when the admin menu is ready to have items added.
@@ -73,7 +73,7 @@ forward OnAdminMenuCreated(TopMenu topmenu);
  * @param topmenu		Handle to the admin menu's TopMenu.
  * @noreturn
  */
-forward OnAdminMenuReady(TopMenu topmenu);
+forward OnAdminMenuReady(Handle topmenu);
 
 /**
  * Retrieves the Handle to the admin top menu.

plugins/include/topmenus.inc

@@ -146,6 +146,11 @@ methodmap TopMenu < Handle
 	// @return              A new TopMenu.
 	public native TopMenu(TopMenuHandler handler);
 
+	// Returns a TopMenu handle from a generic handle. If the given handle is
+	// a TopMenu, the handle is simply casted back. Otherwise, an error is
+	// raised.
+	public static native TopMenu FromHandle(Handle handle);
+
 	// Re-sorts the items in a TopMenu via a configuration file.
 	//
 	// The format of the configuration file should be a Valve Key-Values