IR Sensor Simulator Created

IR Sensor Simulator created, ready for code review.
Also added Mac auto-generated file to .gitignore list.
I'll clarify this, but these are the IR sensor readings, in cm, for each of the four cardinal directions of the vehicle-- forward, port ("left"), aft ("backwards"), and starboard ("right"). On vehicles you typically use Port / Starboard to communicate that the answer to the "your left or mine" question is "the robot's". 

I can change it if there is agreement that it would be beneficial.