T hacks: add new tracer ant0 and a tool to plot ofdm data from usrp or rfsim (output or input) The tool ant0 dumps IQ data to a file (or stdout) as float complex or short. It is needed for a student's project. (Well, we could use record/extract, but it's simpler.) The tool ofdm-plot is used to plot output or input signal from gnb in the frequency domain. May be useful to debug, why not.