headline: RBN set/seeme

29Jan22=======================================================================
1. Implement RBN set/seeme which displays any passing RBN spots for your
   callsign in "raw" format.
28Jan22=======================================================================
1. Add Capabilities Line to logged in users.
2. Make absolutely sure that all DB_Files are closed correctly.
3. Introduce (un)set/debug rbnchan to control the visualisation  of raw RBN
   input lines.