Import all or nothing format

Question import format that takes a Moodle XML file and import all multichoice questions as all or nothing multichoice questions.
Companion of the qtype_multichoiceset plugin
I have been asked several time by teachers how they can change some/all of their multichoice questions into all or nothing (multichoiceset) questions.
This import format plugin takes a Moodle XML file and import all regular multichoice questions changing them into all or nothing questions.
This enables users to export some of their multichoice questions using the normal Moodle XML export format and import them back with this format.
The additionnal benefit of this process is that they now have 2 copies of each question, one using the regular grading scheme and one using the all or nothing grading scheme.
This plugin should go into the question/format/multichoiceset Moodle installation directory. Login as admin to complete plugin installation. Then select this format  Import all or nothing format  during question bank import.
This work is based on the crossxml qformat plugin made by Daniel Thies 2018  dethies@gmail.com  and licensed under the included GPL 3