Refactoring
	modified:   stigame/ComboBox.cpp
	modified:   stigame/GuiItem.cpp
	modified:   stigame/GuiItem.h
	modified:   stigame/GuiOverlay.cpp
	modified:   stigame/GuiOverlay.h
	modified:   stigame/GuiRuntime.cpp
	modified:   stigame/GuiRuntime.h
	modified:   stigame/GuiState.cpp
	modified:   stigame/GuiState.h
	modified:   stigame/RadioGroup.cpp
	modified:   stigame/RadioGroup.h
	modified:   stigame/Style.h