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.
This addresses issues discovered during testing, including:
* inclusion of the M.core_question_preview metadata;
* inclusion of required strings; and
* correcting a function signature.
Add new API for filtering questions, refactoring the options to display
old questions and include subcategories into new
question_bank_search_condition classes. Make the new API pluggable via
local_[pluginname]_get_question_bank_search_conditions.
