Merge from Björn:

* plugin-runner.c (main): Bug fix: For the "--options-for" option, do
                          not mangle arguments with colon characters.
                          Also support adding empty arguments.

* plugins.d/mandos-client.c: (mc): New global variable; moved from
                                   "main".
  (init_gpgme, pgp_packet_decrypt, init_gnutls_global,
  init_gnutls_session, start_mandos_communication): Removed "mc"
                                                    argument.  All
                                                    callers changed.

  (resolve_callback, browse_callback): Ignore "userdata" argument.
                                       All callers changed.
  (handle_sigterm): New function.
  (main): Add "handle_sigterm" as signal handler for SIGTERM before
          starting the main loop.