templates/rss/filelog.tmpl

mq: add --currentdate and --date options to qnew and qrefresh

These options make qnew add and qrefresh update a "# Date "-style
header line. This allows proper recording of creation / last
modification dates of patches in patch queues.

Note that `qrefresh -D` only updates existing header lines. It never
adds them, and does not warn about this. This is because I expect
people to have `[default] qrefresh -D` in their .hgrc so patches with
tracked dates get updated, others are left unchanged. The suggested
setup in .hgrc is, in fact,

  [default]
  qnew = -D -U
  qrefresh = -D

I tried to not mix header styles, so `qnew -D -U` now writes the user in
"# User "-style, while `qnew -U` still writes it "From: "-style. Also, if
`qrefresh -U` must add the user, it does so in "# User "-style if the
header contains a "# HG changeset patch" line. (This is caused by mq
not supporting the "Date: "-style header line at all - a reasonable choice
given its standard date format.)

#header#
    <title>#repo|escape#: #file|escape# history</title>
    <description>#file|escape# revision history</description>
    #entries%filelogentry#
  </channel>
</rss>