imjournal: consolidate goto labels in readjournal()
imjournal: sanitize messages as imuxsock does it

This change makes these directives available for imjournal:
  $ControlCharacterEscapePrefix
  $DropTrailingLFOnReception
  $Escape8bitCharactersOnReceive
  $EscapeControlCharacterTab
  $EscapeControlCharactersOnReceive
  $SpaceNLOnReceive
bugfix: not all files closed on auto-backgrounding startup

This could happen when not running under systemd. Some low-numbered
fds were not closed in that case.

To fix this, the auto-backgrounding startup sequence has been
refactored.
cleanup: rsyslogd -e option has finally been removed

It is deprectated since many years.
cleanup startup processing
refactor init signal handling
testbench: add valgrind test
relicensing

after careful code&git history&extended git history review, all
authors agreed to the relicensing