Fix EDE security flaw involving loading arbitrary Lisp from Project.ede.

Fix EDE security flaw involving loading arbitrary Lisp from Project.ede.

* lisp/ede.el (ede-project-directories): New option.
(ede-directory-safe-p): Check it.
(ede-initialize-state-current-buffer, ede, ede-new)
(ede-check-project-directory, ede-rescan-toplevel)
(ede-load-project-file, ede-parent-project, ede-current-project):
(ede-target-parent): Avoid loading in a project unless it is safe,
since it may involve malicious code.  This security flaw was
pointed out by Hiroshi Oota.

* lisp/ede/auto.el (ede-project-autoload): Add safe-p slot.
(ede-project-class-files): Projects using Project.ede are unsafe.
(ede-auto-load-project): New method.

* lisp/ede/simple.el (ede-project-class-files): Mark as unsafe.