Changing the menu implementation from presenting a new scene to pausing the physics and presenting a menu SKNode
When the main screen is touched, a menu with two “button” appears
The menu appears when the screen is tapped and disappears when you tap the screen again
Merge remote-tracking branch 'origin/master'
Menu now overlays on game (breaks use of game, since it is looking for a touch anywhere on screen
Adds the code to implement a menu that appears on touch (currently commented out to avoid breaking interaction with disk)