quiz: MDL-6085 when editing a question from various places like a preview attempt...

quiz: MDL-6085 when editing a question from various places like a preview attempt or review screen, don't use a popup, instead take advantage of the fact that question.php now takes a returnurl. Merged from MOODLE_19_STABLE.

And MDL-17568 minor niggles with new queston navigation:
* The bit that scrolls down to the question you just submitted in adaptive mode was not working with random questions.
* Teachers reviewing an open attempt were shown the qusetions as editable, not read only!