ox.el: German localization of 'References' section

* lisp/ox.el: Add German localization of the 'References' section

Suggested by Batien Guerry
Fix previous commit
org.el: New alias: `org-highlight-links' -> `org-activate-links'

* org.el (org-highlight-links): Rename from
`org-activate-links'.  Update docstring.
(org-update-radio-target-regexp, org-set-font-lock-defaults):
Use `org-highlight-links'.
Merge branch 'master' of orgmode.org:org-mode