MDL-11090

Passwords are now held in clear text so you can see what the password
is on the config screen.
Still backward compatible with old md5 passwords (which are still not displayed
of course)

mod/lesson/lib.php

@@ -508,9 +508,7 @@ function lesson_process_pre_save(&$lesson) {
     unset($lesson->completed);
     unset($lesson->gradebetterthan);
 
-    if (!empty($lesson->password)) {
-        $lesson->password = md5($lesson->password);
-    } else {
+    if (empty($lesson->password)) {
         unset($lesson->password);
     }