Dragan Dosen 835b9212f6 MEDIUM: log: add a new log format flag "E"
The +E mode escapes characters '"', '\' and ']' with '\' as prefix. It
mostly makes sense to use it in the RFC5424 structured-data log formats.

Example:

log-format-sd %{+Q,+E}o\ [exampleSDID@1234\ header=%[capture.req.hdr(0)]]
2016-02-12 13:36:47 +01:00
..
2015-02-28 23:12:32 +01:00
2016-02-12 11:08:53 +01:00
2009-01-25 13:49:53 +01:00
2015-07-22 00:48:24 +02:00