muse-journal: Publish <qotd> properly for journal-rss and journal-rdf

muse-journal: Publish <qotd> properly for journal-rss and journal-rdf

* lisp/muse-journal.el (muse-journal-markup-tags): Rename from
  muse-journal-latex-markup-tags, because we will use it for
  journal-rss-entry as well.
  (muse-journal-qotd-tag): Move higher.  Use begin-quote-item and
  end-quote-item.
  (muse-journal-rss-munge-buffer): Use journal-rss-entry rather than
  html.
  ("journal-latex", "journal-pdf", "journal-book-latex")
  ("journal-book-pdf"): Use muse-journal-markup-tags rather than
  muse-journal-latex-markup-tags.
  ("journal-rss-entry"): New style that is used by journal-rss and
  journal-rdf to mark up individual entries.  It is needed so that we can
  do something meaningful with the qotd tag.
git-archimport-id: mwolson@gnu.org--2006/muse--main--1.0--patch-393