Sorting in the Permissions tab

Make the column headers in the Permissions tab useable for sorting.

It would make it a lot easier to have, for example, all of the user permissions for a user together, rather than having to search the list for all of the permissions the user has. Currently permissions are listed in order of how they are created, so if I give a user a permission to something today, then in a few weeks give them an additional permission, the permissions will be separated by whatever was created in between that time.