Remove random_string() and replace all calls with get_random_key

These two functions are duplicates of functionality, get_random_key was
written first, and used more often, so makes more sense to keep.
Signed-off-by: Penny Leach <penny@mjollnir.org>

htdocs/admin/users/bulkimport.php

@@ -246,7 +246,7 @@ function bulkimport_submit(Pieform $form, $values) {
             'username'       => $username,
             'firstname'      => 'Imported',
             'lastname'       => 'User',
-            'password'       => random_string(6),
+            'password'       => get_random_key(6),
             'passwordchange' => 1,
         );
 

htdocs/lib/mahara.php

@@ -2283,18 +2283,6 @@ function cron_send_registration_data() {
     }
 }
 
-
-function random_string($length=15) {
-    $pool = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789';
-    $poollen = strlen($pool);
-    mt_srand ((double) microtime() * 1000000);
-    $string = '';
-    for ($i = 0; $i < $length; $i++) {
-        $string .= substr($pool, (mt_rand()%($poollen)), 1);
-    }
-    return $string;
-}
-
 function build_portfolio_search_html(&$data) {
     global $THEME;
     $artefacttypes = get_records_assoc('artefact_installed_type');

htdocs/lib/view.php

@@ -2629,9 +2629,9 @@ class View {
         $data = new StdClass;
         $data->view    = $viewid;
         $data->visible = (int) $visible;
-        $data->token   = random_string(20);
+        $data->token   = get_random_key(20);
         while (record_exists('view_access_token', 'token', $data->token)) {
-            $data->token = random_string(20);
+            $data->token = get_random_key(20);
         }
         if (insert_record('view_access_token', $data)) {
             return $data;