Some fixes to autofill with Unicode usernames; fixed a few end user experience pieces of the group CP. Users are now allowed to freely leave GROUP_OPEN and GROUP_REQUEST groups, and must be removed by a group mod for GROUP_CLOSED and GROUP_HIDDEN.

# Used for testing mod_rewrite.
<IfModule mod_rewrite.c>
RewriteEngine on

RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule (.*) install.php?do=modrewrite_test&str=$1
</IfModule>