Reuse former session of second split. Add destroy function that stops some timeouts.

lib/ace/editor.js

@@ -1123,6 +1123,10 @@ var Editor =function(renderer, session) {
         this.session.getUndoManager().redo();
     };
 
+    this.destroy = function() {
+        this.renderer.destroy();
+    }
+
 }).call(Editor.prototype);