Sorts themes by their names, with the default theme listed first.
Callback for uasort() within system_themes_page().
system_sort_modules_by_info_name().
function system_sort_themes($a, $b) {
if ($a->is_default) {
return -1;
}
if ($b->is_default) {
return 1;
}
return strcasecmp($a->info['name'], $b->info['name']);
}