Try to fix error when loading Muse with muse-project-alist set to nil

Try to fix error when loading Muse with muse-project-alist set to nil

2007-07-10  Michael Olson  <mwolson@gnu.org>

	* lisp/muse-mode.el (muse-grep): Abort search if the current
	project contains no directories.

	* lisp/muse-project.el (muse-project-file-alist): If
	muse-project-alist is not defined, or project is nil, return nil
	right away.  This ought to fix a bug that occurred when using Muse
	with muse-project-alist set to nil.
	(muse-project-of-file): Make sure muse-project-alist is not nil.
	(muse-project-save-buffers): Make sure project is not nil.

	* lisp/muse-wiki.el (muse-wiki-resolve-project-page): Deal with
	case where muse-project-alist is nil.
git-archimport-id: mwolson@gnu.org--2006/muse--main--1.0--patch-383