org-agenda.el: Fix some type strings

* org-agenda.el (org-agenda-max-todos, org-agenda-max-tags)
(org-agenda-max-effort): Fix type strings.
ob-tangle: do not run make-directory with nil argument

* lisp/ob-tangle.el (org-babel-tangle): When `file-name-directory'
  returns nil, do not run make-directory.  Remove superfluous when
  clauses by using short-circuiting `and' instead.

Thanks to R. Michael Weylandt for reporting the problem and offering a
patch.

http://permalink.gmane.org/gmane.emacs.orgmode/85749
http://permalink.gmane.org/gmane.emacs.orgmode/85774
Merge branch 'maint'