The `page_type_list` method for the message component was deprecated
in 5b0769db as part of MDL-54744. However it is still required when
trying to configure blocks on any messaging pages.

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).

Stop using the terms whitelist/blacklist when used to allow/deny things.

* moved the logic from core_message_popup_render_navbar_output to
message_popup_render_navbar_output in message/output/popup/lib.php

* using float: left instead of float: right in theme

This will be used by a new web service and we do not want to fetch
the user unnecessarily in the call.

Also renamed the method for consistency.

Sara Arjona authored Nov 15, 2018 and Jake Dallimore committed Nov 20, 2018

From 3.6 users can have also group conversations, so it's needed to review
the messages_get_messages function to make sure only returns the
individual messages between 2 users.

Unread conversations should be given priority over read. If one or more
sections have unread conversations, prioritise favourites over group and
group over individual. The same applies if all conversations are read.

Changed the settings page in the message drawer to display all message
notification processors (e.g. email, mobile, jabber) for the user to
configure based on which processors are enabled on the site.

* Add clarification to delete messages lang strings
* Stop message polling when sending a message to fix UI bug
* Publish update last message event when polling finds more messages
* Remove logged in user from group conversation participants list
* Use user object to fetch user preferences to reduce DB calls
* Remove animated slide transitions because the browser breaks when
  showing some conversations

Fix some of the behat tests that are looking for generic button
names that match some of the buttons in the message drawer which
happen to appear earlier in the DOM.

* Added missing icon mappings for font-awesome
* Fixed focus on dialogue button when it opens
* Fixed UI updates on user block / unblock
* Fix jQuery syntax error when sending message with quotes
* Fix message/index.php opening drawer when no conversation found
* Fix placeholders rendered for new requests

* Fix navigation from view_contact to view_conversation on an action
  such as blocking
* Fix default open message section on overview page depending on which
  section has conversations
* Fix message/index.php for users who haven't yet started a
  conversation

Add new messaging profile preferences to allow users to choose who
can message them:
- By default, users can select between 'My contacts only' and 'My
contacts and anyone in my courses'
- When $CFG->messagingallusers is enabled, a new option is displayed
also: 'Anyone on the site'. For users who have selected this option,
if $CFG->messagingallusers is disabled, the behaviour will be changed
to 'My contacts and anyone in my courses'

Also deprecated the following functions -

1. message_move_userfrom_unread2read - It is not necessary
   for us to mark a message as read on user deletion.
2. message_get_blocked_users - Horrible logic used to
   determine if a user is blocked via reference on some
   randomly chosen 'isblocked' variable.
3. message_get_contacts - The same as above. This can be
   done in a much nicer way.
4. message_mark_message_read - We want two functions to do
   this to avoid confusing messages and notifications.
5. message_can_delete_message - This assumed the variable
   $message contained the 'useridto' property, which
   was present in the old table structure. We do not want
   future usages where a query is done on the new table
   and is simply passed as this won't contain this property.
6. message_delete_message - Same as above.