MDL-43089 Give question number field minimum width
MDL-43089 Align question items vertically
Removed left padding for page content
MDL-43089 consistent use of html_writer::div && improve qbank ajax.
MDL-43089 continue the renderer logic cull.
MDL-43089 a way to add a question on a new page at the end.
MDL-43089 move question_per_page options out of renderer.
MDL-43089 action menu should open downwards.
MDL-43089 fix page split/join icons.

Embarassingly, the SVG filenames were the wrong way around.
MDL-43089 eliminate non-shiftered edit.js.
MDL-43089 start to clean up the structure class.