Added the start of the comm subsystem

Figured out the apparent best way to code the Link class and how to pass
Link Settings around. Got rid of the idea to derive subclasses from
Link. Started to code the Message and Protocol classes.
Updated all windows to make use of comm Link

Now using the Settings in Link when saving state for each comm setup
dialog. Added a main Link object in MainWindow which is how all data
will be uploaded to and downloaded from external vehicles.