(time-stamp-string-preprocess): Don't just call format-time-string;
handle compatibility for some old constructs. Handle padding
the historical way, while giving a warning if people actually depend on it.
(time-stamp-conv-warn, time-stamp-conversion-warn)
(time-stamp-do-number): New functions.
(time-stamp-format): Use %Y not %y in default value.
(time-stamp): Verify time-stamp-line-limit is a number.
(time-stamp-string-preprocess): Handle %F correctly.
(time-stamp-weekday-full-names): Likewise.
(time-stamp-weekday-numbers): Likewise.
(time-stamp-old-format-warn): Doc fix.
(time-stamp-strftime): Function deleted.
(time-stamp-string): Use format-time-string.
(time-stamp-format): Change default value
to work with format-time-string.
(time-stamp-strftime): ignore some additional chars we might want
to use in the future for additional controls or parameters.
(time-stamp): minor optimizations.
functions with string containing %-escapes in the style of date(1).
(time-stamp): Widen buffer while time-stamping.
(time-stamp-toggle-active): New function.
(time-stamp-warn-inactive): New variable.
(time-stamp-mail-host): Now a user option.
(time-stamp-current-year, time-stamp-hh:mm): Removed.
(time-stamp-mm/dd/yy, time-stamp-dd/mm/yy): Removed.
(time-stamp-yyyy-mm-dd): New function, ISO 8601 format.
