* lisp/org.el (org-startup-numeroted): New option.
(org-startup-options): New "num" and "nonum" startup keywords.
(org-mode): Startup according `org-startup-numeroted' or the
local #+startup setup.
* doc/org-manual.org (Dynamic Headline Numbering)
(Summary of In-Buffer Settings): Document
`org-startup-numeroted' and #startup: num.
* etc/ORG-NEWS: Document the new startup option.
Thanks to Guillaume MULLER for this idea.