implemented saving UI

Implemented the file dialog, save progress dialog, and separate thread to save
in (saving needs to be done in a separate thread so the main/GUI thread doesn't
get blocked).

app/panel/project/project.h

@@ -58,6 +58,8 @@ private slots:
   void ItemDoubleClickSlot(Item* item);
 
   void ShowNewMenu();
+
+  void ProjectNameChanged();
 };
 
 #endif // PROJECT_PANEL_H