improve at-end error logging
improve at-end error logging

always use archiver.print_error, so it goes to sys.stderr

always say "Error: ..." for errors

for rc != 0 always say "Exiting with failure status ..."

catch all exceptions subclassing Exception, so we can log them in same way and set exit_code=1

raxenak/borg,RonnyPfannschmidt/borg,mhubig/borg,edgewood/borg,edgewood/borg,edgimar/borg,RonnyPfannschmidt/borg,ionelmc/borg,edgewood/borg,mhubig/borg,level323/borg,raxenak/borg,RonnyPfannschmidt/borg,RonnyPfannschmidt/borg,ionelmc/borg,ionelmc/borg,edgewood/borg,edgimar/borg,raxenak/borg,raxenak/borg,RonnyPfannschmidt/borg,level323/borg,level323/borg,mhubig/borg,edgimar/borg,edgimar/borg