Author: Jetha Chan
MDL-48542 user_menu: add proper divider support
Added divider support to the user menu; hardened the custom user menu against invalid input.
http://git.moodle.org/gw?p=moodle.git;a=commit;h=2dfdb127b624cfa511cfcd22fc47cffb31e11567
http://github.com/moodle/moodle/commit/2dfdb127b624cfa511cfcd22fc47cffb31e11567
+ 2.8 en [configcustomusermenuitems,core_admin]