I need to be able to submit logs to a log server in RFC5424 format, but I don't want to change the format of local log files. I added a -r option that controls only the format of network destinations. I've given up my commit bit, so if this is accepted I'll be trying to recruit a src committer to push this.
Restructured to use an enum for output formats rather than a bool, making it easier to change the defaults or add additional formats in the future. This was rebased onto 13.2 as a part of our migration; I haven't checked whether it still applies to 14-current.