better argument documentation of display routines
add sim network connection mode

The SIM_INPUT_NET ifdef makes a network connection talk to the command
interface instead of HPIB. Used to aid remote debugging of menu mode.
fix reset key ignored bug

For reasons that are not understood, when the -O3 optimized version of
the app are run in auto-start mode the reset key push is not detected
most of the time unless a delay is added. Oddly, this bug doesn't
appear if the optimized version is run from the command line, which
makes no sense. It doesn't appear to be code getting optimized away or
a missing volatile declaration but rather timing related.