MDL-32729 Question: Correct button selection when openin qbank chooser

Some browsers do not bubble form submission events to the window, and we
had more than one form on the page in certain conditions. We need to select
all of the forms on a page and then test the action.
MDL-32729 Question: Load all hidden fields from the source form
Merge branch 'MDL-32729-im' of git://github.com/andrewnicols/moodle
MDL-44078 all callbacks in standard Moodle