Teach configtool to save ini, board and printer files with the
--save commandline switch. Add a feature to Printer and Board
to let us pass None for the "values" to save; this causes the
class to save the previously loaded settings instead of taking
new settings in the argument.
Also add --quit switch to tell commandline not to continue to run the
GUI. There's not much point in running the gui after many of these
switches, but that will change in the future. Add this --quit option
to quit early so we can begin to use this new mode for test validation.
Instead of passing myriad variables around in arguments to
classes and functions, put the global settings like "verbose" and
"cmdFolder" in the Settings object and pass that in to the top.
Move model functionality out of printerpanel.py into a new class,
Printer, so we can more easily add commandline driven tests in
the future and to help identify code reuse opportunities.