Fix #5925: Emphasis on item breaks lists.

Fix #5925: Emphasis on item breaks lists.

* lisp/muse-blosxom.el ("blosxom-html", "blosxom-xhtml"): Use find-file
  as the browsing function.

* lisp/muse-mode.el (muse-browse-result): Only include styles that match
  the current file.

* lisp/muse.el (muse-list-item-critical-point): Take a new argument named
  `offset' into account, in case the list-item regexp is nested in
  another group.
  (muse-forward-list-item): Call `muse-list-item-critical-point' with an
  offset of 1.  This should fix an unpleasant list-as-blockquote error
  that was noticed recently.  Thanks to John Sullivan for the report.
git-archimport-id: mwolson@gnu.org--2006/muse--main--1.0--patch-125