Menu and menu infrastructure.

Added intersection method with points
Implemented a button class partly
Changed version number to 0.3

	new file:   physics/Button.cpp
	new file:   physics/Button.hpp
	new file:   physics/Menu.cpp
	new file:   physics/Menu.hpp
	new file:   physics/MenuItem.cpp
	new file:   physics/MenuItem.hpp
Add registering mouse and key actions to games.

Fully implemented the button class.