Renamed CGuiHandler to GameEngine

- class CGuiHandler is now called GameEngine to better describe its
functionality
- renamed global GH to more clear ENGINE
- GH/ENGINE is now unique_ptr to make construction / deconstruction
order more clear and to allow interface / implementation split
- CGuiHandler.cpp/h is now called GameEngine.cpp/h and located in root
directory of client dir

client/mapView/MapViewActions.cpp

@@ -16,7 +16,7 @@
 
 #include "../CGameInfo.h"
 #include "../adventureMap/AdventureMapInterface.h"
-#include "../gui/CGuiHandler.h"
+#include "../GameEngine.h"
 #include "../gui/CursorHandler.h"
 #include "../gui/MouseButton.h"
 
@@ -155,7 +155,7 @@ void MapViewActions::hover(bool on)
 {
 	if(!on)
 	{
-		GH.statusbar()->clear();
+		ENGINE->statusbar()->clear();
 		CCS->curh->set(Cursor::Map::POINTER);
 	}
 }