Use ISO 8601 date format, with time zone appended if

Use ISO 8601 date format, with time zone appended if
change-log-time-zone-rule is non-nil, instead of traditional Unix date
format.

(datearg): When computing default from ChangeLog, handle ISO format dates
in addition to old-fashioned dates from Emacs 19.31 and earlier.  Don't
worry about hh:mm:ss since the resolution is now by day.  Use emtpy
datearg, not empty rlog_options, to decide whether to pass "$datearg"
option to $rlog.
(logTZ): New variable, set to TZ specified by change-log-time-zone-rule.
(month_data): Remove `mo'; no longer needed.
(rlog_options): Use -zLT for localltime output, if `rlog' supports it.
(extractTZ): Use UTC if the zone is t.

Match `revision' line of rlog output more accurately.

Add -c, -v options.