fix regex to handle the structured data field in syslog
handle escaped right brackets in the syslog structured data field to conform to rfc5424
Adding tests for RFC5424 parsing of meta fields
Merge branch 'rfc5424-sdata-processing-fix' into v67.1
Upgrade paths

v66->v67 will automatically work for v67.1 on top of v67 given the
    purely functional changes brought to the library.
v67->v67.1 will just reload the two changed modules.
Merge branch 'v67.1'