This commit replace as much as possible of clean_param and PARAM_ usages related to user object.
Also few unit tests has been changed to match the new validation
This is intended as a revision counter for local modinfo caching. It should be a lot more reliable and faster than doing it in PHP. Please note you need to invalidate all course caches after using this.
This function used to be in the user selector, but it is useful in
other areas where we want to search for users as it handles a number
of search options (including extra fields, etc.) and returns SQL
which can be included in a joined query.
A unit test has been added to check the results of these searches.
The purpose of this method is to ensure that when we display lists of
users in different places, the default sort order is consistent.
Having this code centralised in one place them makes it possible to
improve things accross the board, and there is an example of that here.
There is logic so that if we are searching for particular string, then
users with an exact match are sorted first.
