Clean up forum post report timestamps.

(1) Stop mangling the nice standard ISO 8601 datestamps into… some
perverted format that as far as I know isn’t even really used anywhere.

(2) Stop capturing sequential elements of the input then outputting them
idem; merge these needlessly separate captures.

(3) Stop capturing elements of the input that are not subsequently used;
delete these unnecessary captures.

(4) Merge the needlessly separate $data_date variables into the
$data_time variables.

(5) Include timezones in the timestamps.