Calibration setup bug fixes

Incorrect naming of variables in config file
ruggedization, functions to read back

access to configuration parameters now through get_beam_param, get_param
where try except blocks help identify missing parameters.

read_int and bf_read_int added that allow reading values back.

set_centre_frequency_bandwidth changed to set_bandpass
set_bandpass now stops transmission and restarts with changed
bandpass settings

get_centre_frequency, get_bandwidth combined into get_bandpass