Users screen: add sorting and filtering

[Adam P]

NOTE: THIS ITEM NEEDS FURTHER SPECIFICATION BASED ON ADMIN INPUT

Add ability to sort and filter users on the Users list page (users.php). Currently there is no such functionality -- just an unwieldy flat list of users.
Also, display the total number of users, and the number of users matching the current filter.
Also, display users in pages (of 100, configurable in config.php), instead of trying to load and display all at once.
Filter criteria: user types, others?.
Sort criteria: primary sort by column only.

[Adam P (adam+)]

Possibly also default to no users listed -- currently it's slow to show the screen.

[Adam Kruger (adam-kruger)]

Display users in pages, instead of trying to load and display all at once

[Robert Vasilev (vasilev)]

Hello, Psiphon Inc .
Is here intends for implementing user filtering ?
Can we use AJAX or another JavaScript technology ?
Or it is intended to implement JavaScript-free solution ?

[Robert Vasilev (vasilev)]

Completely JavaScript-free filtering solution has been implemented.

[Robert Vasilev (vasilev)]

1. Implemented paging in users.php (inspired by reports.php).
2. Implemented column sorting in users.php (inspired by tickets.php).
3. Implemented filtering by user class.