All flowgraphs now support user defined parameters for most of their
configuration capabilities. These include:
* RF gain
* IF gain
* BB gain
* Custom device arguments for setups with multiple SDRs. These
coresponds to the 'Device arguments' field of the Osmocom source block.
* Antenna selection for devices with multiple antennas (USRPs, etc)

Changing sampling rate is not supported (yet).

For listing the arguments just execute <flowgraph> --help in a terminal
window.