Begin implementing context-specific handling of special characters.

Begin implementing context-specific handling of special characters.

* lisp/muse-publish.el (muse-publish-url-transforms)
  (muse-publish-desc-transforms): Remove
  muse-publish-escape-specials-in-string, since we will explicitly call
  this with the proper parameters later on.
  (muse-publish-escape-specials, muse-publish-escape-specials-in-string):
  Add new optional CONTEXT argument that specifies further information to
  use when obtaining the specials that will be applied to the text.  If
  someone specifies a function instead of an alist for the style's
  specials, call it and pass CONTEXT.
  (muse-publish-markup-word): Indicate the context when escaping
  specials.  Make sure we have a context before continuing the publishing
  of the word.
  (muse-publish-markup-email, muse-publish-markup-url)
  (muse-publish-code-tag, muse-publish-example-tag)
  (muse-publish-verbatim-tag): Indicate the context when escaping
  specials.
  (muse-publish-url): Explicitly escape specials, rather than expecting
  it to be done in a user-customizable hook.  Use different contexts for
  url and description.
git-archimport-id: mwolson@gnu.org--2005/muse--main--1.0--patch-310