This class would belong more appropriately within the 'user' API
(core_user) instead of within the 'core' API, since it is
directly related to user data.

Since the class has only just been added to Moodle, now is a good
time to move it.

In all cases changes have been kept to a minimum while not making
the code completely horrible. For example, there are many instances
where it would probably be better to rewrite a query entirely, but
I have not done that (in order to reduce the risk of changes).

Padding nested course categories by space to make them render in a tree
structure does not really make a lot of sense as they are already being
rendered as full paths. It's simpler to show them without the
indentation.
Given this, there's not much point keeping make_categories_options().
So it's better to deprecate this function and call
core_course_category::make_categories_list() directly instead.

If you try to visit a category where another user is deleting a
course the coursecat cache may not be fresh. This is because there
is a breif time where the course record will have been deleted,
while it is deleting other course information, before the event that
triggers the coursecat cache to be purged is fired.

Or when a course category is moved/deleted

Introduce new hooks for plugin developers:

  - <component>_can_course_category_delete($category)
  - <component>_can_course_category_delete_move($category, $newcategory)
These hooks allow plugin developers greater control over category deletion. Plugin can return false in those
functions if category deletion or deletion with content move to the new parent category is not permitted.

  - <component>_pre_course_category_delete_move($category, $newcategory)
This hook is expanding functionality of existing <component>_pre_course_category_delete hook and allow plugin developers
to execute code prior to category deletion when its content is moved to another category.

 - <component>_get_course_category_contents($category)
This hook allow plugin developers to add information that is displayed on category deletion form. Function should
return string, which will be added to the list of category contents shown on the form.

it is quite often when we need to have an autocomplete element that searches courses that
have completion enabled. This commit adds an option for the 'course' form element, and also
changes two places where we search for courses with completion. This should fix MDL-58989

This commit is part of work on Custom fields API,
to minimize commit history in moodle core the work of a team of developers was split
into several commits with different authors but the authorship of individual
lines of code may be different from the commit author.

This chagne adds support for a new feature known as Context Locking.
This allows a context to be locked, thereby removing all write
capabilities for all users (including admin) for that context, and all
child contexts.

Thanks to MDL-49398, we can separate the combined user session and role
definition cache clearing function into two separate functions. At the
same time, we want to identify and remove mark_dirty() calls that were
added for role definition changes but were incorrectly left behind.

Change highlights:
 - Remove unnecessary mark_dirty() calls performed after
   assign_capability(), unassign_capability(), delete_role(),
   deleted contexts, brand new contexts
 - Move role definition cache clear from the user-centric
   accesslib_clear_all_caches() to the newly created,
   role-dedicated accesslib_reset_role_cache()

Also rename course_in_list -> core_course_list_element
Deprecate class coursecat_sortable_records

Replace calls to \coursecat::get_all() or cache the results.

When the course category cache needs to be repopulated, two entries are added
to the cache for each category. In core this is currently done in a for-loop,
resulting in N set calls to the cache (where N is twice the number of
categories in Moodle).

This change switches that code to using a single set_many cache call instead,
which makes this an O(1) operation instead of O(N).

For a site with say, 1000 categories, this results in only 1 set call to the
cachestore instead of 2000.

Users should be able to remove an idnumber from a category, before this
change when trying to delete an idnumber users would be told it already
existed.

This change also stops 0 from being allowed multiple times as an idnumber.

This is a squashed commit containing a number of changes:

This is an ajax driven course selector that has searching etc. It can select single, or multiple courses.
Make course selector accept a list of courses to exclude
courseselector - lookup coursename on setValue
Use the get_course_display_name_in_list function to generate the course names
Add a throttle to auto-complete to reduce spamming the server
Do a single query to fetch all the courses in the mform element when validation fails
Fix core course search function to return results when there are less than 2 chars in the query.
Handle setData with an empty array in new course selector