Apply a few fixes from Yann's branch.

Apply a few fixes from Yann's branch.

Background: I hacked on Muse over the weekend while offline, and so did
            Yann.  His changes to muse-wiki.el are different than the
            ones that I made, so we should probably figure out the best
            way to handle this when we both get on IRC again.  For now,
            I've merged in the bugfixes that he's made, omitting most of
            the changes to muse-wiki.

* lisp/muse-latex.el (muse-latex-markup-regexps): Escape %.

* lisp/muse-wiki.el (muse-wiki-colors-wikiword): Add docstring.

* lisp/muse.el (muse-page-name): Fix a bug that was inadvertently
  introduced previously.

git-archimport-id: mwolson@gnu.org--2005/muse--main--1.0--patch-87