Add `muse-current-file', fix minor QuickStart issue.
* examples/QuickStart: Make John Wiegley the author.
* lisp/muse-blosxom.el (muse-blosxom-markup-date-directive): Use
`muse-current-file' instead of `buffer-file-name'.
* lisp/muse-project.el (muse-current-project): Document.
* lisp/muse-project.el (muse-current-file): New variable indicating the
name, including path, of the file that is currently being published.
(muse-project-of-file): Make use of
`muse-current-file'.
* lisp/muse-publish.el (muse-publish-file): Set `muse-current-file' here.
* lisp/muse.el (muse-page-name): Make use of `muse-current-file'.
git-archimport-id: mwolson@gnu.org--2005/muse--main--1.0--patch-78