planner-calendar: Make « and » work

planner-calendar: Make « and » work

* planner-calendar.el (planner-calendar-prev-month-href)
  (planner-calendar-next-month-href): Don't escape specials specials in
  the URL description.  This should fix a bug with "«" and
  "»".

* planner-publish.el (planner-publish-ignore-url-desc-specials): New
  variable that determines whether to ignore specials in URL
  descriptions.
  (planner-publish-decide-specials): New function that uses this
  variable.
  ("planner-xml", "planner-xhtml", "planner-xhtml"): Set :specials to
  planner-publish-decide-specials.

git-archimport-id: mwolson@gnu.org--2006-planner-el/planner-el--devel--0--patch-125