I first want to break out the port I/O kernel (really stolen from Rune)
so that multiple nanoVNA commands may be sent in a single nVargs.py invocation
nVargs.py now implements multiple commands per invocation, surrounded by (unlogged) `pause` and `resume`
Both it and nVcmd.py are tweaked to eliminate redundant trailing newline.
If e.g. nanVNA is calibrated for four frequency bands:
50-658, 666-8660, 9800-114000, 126000-1500000
.. then a single invocation can collect data for all four bands, e.g.
py nVargs.py "recall 0" "data 0" "recall 1" "data 0" recall 2" "data 0" "recall 3" "data 0"
Double-quotes are required for passing multi-word commands to the script as e.g. 8, rather than 16, arguments..
Output for all for sets of data redirect to a single file.
Oristo