Added role and aria-expanded attributes to the toggler link and added
a key handler for the space and enter keys.

Converting the uses to the AMD modules is a bit risky for now, instead
just require the YUI depdency.

get('blah') are for properties
get_blah() are for helpers

Helper methods (ie custom methods on a persistent) should not be callable via set() or get() even
if they start with set_ or get_. They are not the same as custom getters and setters for real persistent
properties.

I missed all the entry pages when converting from set_abc() and get_abc() to set('abc', ) and get('abc').

Also fixed a wrong namespace for core_competency\external\performance_helper

Merge branch 'wip_master_mdl-50625_ldap_better_check_paged_results_support' of https://github.com/iarenaza/moodle

* Add some missing example contexts
* Stop using obsolete cell attributes