Generalize some blosxom helper functions.

Generalize some blosxom helper functions.

* examples/mwolson/muse-init.el (muse-project-alist): Adapt to new
  generalized helper functions.
  (my-muse-prepare-entry-for-xanga): Use muse-blosxom-extension rather
  than hard-coding it.  Use muse-with-temp-buffer.  Handle all kinds of
  relative links.

* lisp/muse-blosxom.el: Update example in header.
  (muse-blosxom-new-entry): Use new names for helper functions.
  (muse-blosxom-get-categories, muse-blosxom-project-alist-entry)
  (muse-blosxom-project-alist-dirs): Move to muse-project.el.

* lisp/muse-project.el (muse-project-recurse-directory): Renamed from
  `muse-blosxom-project-get-categories'.
  (muse-project-alist-styles): Renamed from
  `muse-blosxom-project-alist-entry'.
  (muse-project-alist-dirs): Renamed from
  `muse-blosxom-project-alist-dirs'.
  (muse-project-of-file): Use `muse-current-file'.

* lisp/muse-wiki.el (muse-wiki-resolve-project-page): Use
  `muse-current-file'.

* lisp/muse.el (muse-current-file): New function that returns the name of
  the currently visited or published file.
  (muse-page-name): Use `muse-current-file'.
git-archimport-id: mwolson@gnu.org--2005/muse--main--1.0--patch-183