* Allow multiple roles to be allocated by identity provider
* Allow existing enrolment plugins to manage mnet enrolments
Author: Peter Bulmer <peter.bulmer@catalyst.net.nz>
When usernames are numeric, they are lost in mnet transit when used as
keys in the array result of course_enrolments(). As the username is not
sent with the enrolment details, it was not previously recoverable.
This patch adds the information to the enrolment details,
(enrol/mnet/enrol.php), and adds support for recovering the username if
it was numeric (and hence lost) (admin/mnet/enr_course_enrol.php)
* improved handling of dirty contexts in general - caching, switching in cron, marking, loading, etc.
* role_assing() and role_unassign() now marks dirty contexts because we use has_capability() in this function - we can not do it later outside to speedup bulk operations
* fixed some inline docs
* fixed notice from rs closing
* removed cached $CONTEXT from has_capability() - $context is now required parameter; this was hiding serious bugs when context did not exist or ppl passed false as parameter
* removed some ===, we can not use these on function parameters - we must support ints, strings, '', nulls, etc. - this could be a source of really dangerous bugs in future
* some other improvements and fixes - documented inline
- ensure addslashes() affects data that goes to the database, not HTML
- ensure we return defaultrolename from avaiable_courses
- clear some leftover debug statements
