datalib: get_my_courses() - some fixes to the data we return

strangely, get_my_courses() is expected to return the
array keyed on id, which messes up the sorting

So let's do it ;-)

lib/accesslib.php

@@ -1796,8 +1796,6 @@ function get_user_access_bycontext($userid, $context, $acc=NULL) {
 function load_all_capabilities() {
     global $USER,$CFG;
 
-    unset($USER->mycourses);        // Reset a cache used by get_my_courses
-
     static $defcaps;
 
     $base = '/'.SYSCONTEXTID;