Added window grouping for dwindle

furthermore, added LayoutRenderHints.

src/managers/KeybindManager.hpp

@@ -32,6 +32,8 @@ private:
     void                fullscreenActive(std::string);
     void                moveActiveToWorkspace(std::string);
     void                moveFocusTo(std::string);
+    void                toggleGroup(std::string);
+    void                changeGroupActive(std::string);
 };
 
 inline std::unique_ptr<CKeybindManager> g_pKeybindManager;