Use separate escaping for embedded images.

Use separate escaping for embedded images.

* NEWS: Update through patch-95.

* lisp/muse-latex.el (muse-latex-markup-specials-url): Use
  \textbackslash{} for "\".  Thanks to Jim Ottaway for the suggestion.
  (muse-latex-markup-specials-image): New option that enables escaping of
  specials in images.  This was split from the URL specials.
  (muse-latex-decide-specials): Handle 'image context.

* lisp/muse-publish.el (muse-publish-escape-specials): Document 'image
  context.
  (muse-publish-url): Use 'image context for images.

* lisp/muse-texinfo.el (muse-texinfo-decide-specials): Treat images the
  same as URLs.

* lisp/muse-xml-common.el (muse-xml-decide-specials): Ditto.
git-archimport-id: mwolson@gnu.org--2006/muse--main--1.0--patch-176