dirname() is a slow function compared with __DIR__ and using
'/../'. Moodle has a large number of legacy files that are included
each time a page loads and is not able to use an autoloader as it is
functional code. This allows those required includes to perform as
best as possible in this situation.
List of changes:
* configurable unenrol action
* new setting for synchronisation of all enrolled users or users with at least one role
* cron period increased to 1 hour in order to lower server load, courses should not get out of sync often
* CLI sync script for debugging or manual sync
* phpdocs fixes
* when plugin is disabled all roles are removed, enrollments are kept
* uninstall script
* other bugfixing