output-lua: rule info callback

output-lua: rule info callback

SCRuleIds(): returns sid, rev, gid:

    function log(args)
        sid, rev, gid = SCRuleIds()

SCRuleMsg(): returns msg

    function log(args)
        msg = SCRuleMsg()

SCRuleClass(): returns class msg and prio:

    function log(args)
        class, prio = SCRuleClass()
        if class == nil then
            class = "unknown"
        end