This implementation will introduct changes to
the mod_quiz to implement the new qbank api
for view. Major changes are introduced in
the custom view and also all the legacy points
to the old qbank are changed to qbank plugins
where needed. It also deprecated and deletes
classes and scripts which were kept not to
break mod_quiz for the new api implementation.
This implementation will introduce a qbank plugin "managecategories"
which will add the question categories feature in the question bank view
by replacing the core classes. Having this plugin will give users
the flexibility of enabling or disabling the category tab.
