PS3 controller is not compatible with Jetson Nano

Update setup_jetson_nano.md docs with the correct unversioned directory names

Update supported_cars.md

At lines 103-104 the mv command removes the version IDs from the directory names for opencv and opencv_contrib.  This change makes the cmake command starting on line 123 consistent with these directory names.

Minor update to RotaryEncoder in encoder.py part (fix shutdown code)

Add axis names and button names to Joystick.

Fixes issue where images come out as BGR instead of RGB for Jeston Nano

Detect loading of unrecognised model file types.

Add 'else' clause to loading model files to capture unknown file extension types (i.e. NOT .h5 or .json)

* This makes controlling the car with the triggers intuitive.
* Right trigger to accelerate.
* Left trigger to decelerate.

* This step helps discover mappings not already pre-existing and
provides a way to dicover and modify defaults.

* Adds Forza mode for the XboxOne controller.

Fix training split (issue 406)

Reintroduce the much improved Calibrate function