Move defvars out of eval-when-compile. Use

Move defvars out of eval-when-compile.  Use
	buffer-file-name variable.
	(org-agenda-file-to-end, org-agenda-file-to-front): Remove unused
	arg `file'.
	(org-level-faces): Remove startup dependency.
	(org-cycle, org-map-tree, org-scan-tags)
	(org-remember-handler): Don't call `outline-level' directly.
	(org-mhe-search-all-folders): New option.
	(org-mhe-get-message-folder-from-index,
	org-mhe-get-message-folder): Fix indexing search.
	(org-format-agenda-item): Handle nil TAGS argument.
	(org-cleaned-string-for-export, org-activate-target-links)
	(org-make-target-link-regexp): Deal with empty radio target list.
	(org-tag): New face.
	(org-get-level-face): New function.
	(org-set-font-lock-defaults): Simplify setup for headlines.
	(org-complete): Pass common substring to `display-completion-list'.