Updated Leap lib to 2.0, integrated GestureReader
-CODE: Updated Leap Motion library and binaries to v2.0-beta.
-CODE: Patched Marker and the "pause gesture" to work with skeletal
tracking. 
-CODE: Changed Menu to an abstract class instead of an interface.
-CODE: Moved the menus' panel_-variables into Menu instead.
-CODE: Integrated GestureReader into the project to ease gesture
recognition.
-BUG: Some gestures were not recognised properly (since the game's FPS
is lower than the Leap's FPS).