ajaxlib/require_js: MDL-16693 $PAGE->requires->... deprecates require_js etc.

There is a new implementation of require_js in lib/deprecatedlib.php,
based on $PAGE->requires.

There were a few other recently introduced functions in lib/weblib.php,
namely print_js_call, print_delayed_js_call, print_js_config and
standard_js_config. These have been removed, since they were never in
a stable branch, and all the places that used them have been changed
to use the newer $PAGE->requires->... methods.

get_require_js_code is also gone, and the evil places that were calling
it, even though it is an internal function, have been fixed.

Also, I made some minor improvements to the code I committed yesterday
for MDL-16695.

All that remains is to update all the places in core code that are
still using require_js.

(This commit also fixes the problem where the admin tree would not
start with the right categories expanded.)

lib/questionlib.php

@@ -2110,7 +2110,7 @@ function question_format_grade($cmoptions, $grade) {
  * to get from PHP.
  */
 function question_init_qenginejs_script() {
-    global $CFG;
+    global $CFG, $PAGE;
     $config = array(
         'pixpath' => $CFG->pixpath,
         'wwwroot' => $CFG->wwwroot,
@@ -2119,7 +2119,7 @@ function question_init_qenginejs_script() {
         'flaggedalt' => get_string('flagged', 'question'),
         'unflaggedalt' => get_string('notflagged', 'question'),
     );
-    return print_js_config($config, 'qengine_config', true);
+    $PAGE->requires->data_for_js('qengine_config', $config);
 }
 
 /// FUNCTIONS THAT SIMPLY WRAP QUESTIONTYPE METHODS //////////////////////////////////