com.jme3.input.controls package allows user code to listen
to input events regardless of the type of input used.
ActionListener is used to receive input events in "digital" style.
AnalogListener is used to receive events of inputs
in analog format.
TouchListener is used to receive events of inputs from smartphone touch devices
A trigger represents a physical input, such as a keyboard key, a mouse button, or joystick axis.
KeyTrigger is used as a mapping to keyboard keys.
MouseAxisTrigger is used as a mapping to mouse axis,
a mouse axis is movement along the X axis (left/right), Y axis (up/down)
and the mouse wheel (scroll up/down).
MouseButtonTrigger is used as a mapping to receive events
from mouse buttons.
Class to trigger TouchEvents, keycode can be TouchInput.ALL(=0) or TouchInput.KEYCODE_*