Added autopilot. Steering much improved.

Version 0.3 has a new icon (Steering Wheel)
There is an autopilot type control as well as the tiller.
Auto starts that control. Use 'Standby' to return to tiller steering.
Better presentation of heading.
Tracking is much improved, showing a smooth course.

2018-01-05: The zip file contains ais messages you can use with ShipDriver.