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.
Removed the concat to generate the uniqueid field for the popup
notifications data. The concat can't be used directly in the SQL because
the syntax changes between databases. The sql_concat helper can't be
used because it assumes all values are database columns (which they
aren't in this case).
Instead I've just removed the uniqueid field because it isn't required
for the union all to work and the field isn't being used by anything.
This should fixed the compatibility issues between databases.