Fix some wording
Add cabrillo definition for ARRL Sweepstake
Simplify writing cabrillo header

- Until now the cabrillo header was written to a separate file by
  'getsummary()' and finally copied together with the formatted
  QSO-lines. Changed it so that we write the header direct to the
  final file and therefore can drop the copying.
Rework to support Cabrillo v3.0 format

- refactor code to ask for input
- export that code
- write some entries only to cabrillo file if user provided some input
Refactor

- move control of cluster display out to calling context
- reuse code to ask for sent exchange
- drop unused external variable declarations
Reread contest rules file after edit of logcfg.dat with :SET or :CFG
Fix handling of errors; move status messages
Merge branch 'cabrillo'