[ui] Refactor view stack to take a GraphicDisplay

This way it can be specialized with a monochrome or color display later.

Author: MatthewMArnold

src/modm/ui/menu/communicating_view_stack.hpp

@@ -29,7 +29,7 @@ namespace modm
 	class CommunicatingViewStack : public ViewStack
 	{
 	public:
-		CommunicatingViewStack(modm::ColorGraphicDisplay* display, xpcc::Communicator* communicator) :
+		CommunicatingViewStack(modm::GraphicDisplay* display, xpcc::Communicator* communicator) :
 			ViewStack(display),
 			communicator(communicator)
 		{

src/modm/ui/menu/view_stack.hpp

@@ -39,7 +39,7 @@ namespace modm
 	class ViewStack
 	{
 	public:
-		ViewStack(modm::ColorGraphicDisplay* display);
+		ViewStack(modm::GraphicDisplay* display);
 
 		virtual ~ViewStack();
 
@@ -74,7 +74,7 @@ namespace modm
 		/**
 		 * @brief getDisplay access underlying GraphicDisplay
 		 */
-		inline modm::ColorGraphicDisplay&
+		inline modm::GraphicDisplay&
 		getDisplay()
 		{
 			return *this->display;
@@ -100,7 +100,7 @@ namespace modm
 		shortButtonPress(modm::MenuButtons::Button button);
 
 	protected:
-		modm::ColorGraphicDisplay* display;
+		modm::GraphicDisplay* display;
 		modm::Stack< modm::AbstractView* , modm::LinkedList< modm::AbstractView* > > stack;
 	};
 }