Git commits in Moodle 2.2.3 by Ray Guo

commit d6b01141a1af9e53ad79f40ae1d4cccc96c45dff
Author: Ray Guo <r.guo@open.ac.uk>
Date:   Tue, 03 Apr 2012 21:38:47 +0800
Tag:    v2.2.3

MDL-29174 Remove the empty modulename_extend_navigation() stub from 7 modules.