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.)