- Updated pointer to move within content DOM so that you can back-focus
into the pointer if desired.
- Added new "Section select mode" which toggles focusabiltiy for main
content sections, with ability to show pointer via enter press on
these.
- Updated pointer with proper input/button labelling.
Tested via orca screen reader on Firefox/Fedora/Gnome.
For #3975
- Fixes existing broken attachment edit tabs.
- Redesigns area to move away from old tabbed interface.
- Integrates new dropzone system, for both addition and edit.
This is to encourge the ":count" values to be used instead of 1s in the
translated variants so that non-pluralised languages are hardcoded with
"1"s in their content, even when not used in a singular context.
For #4040
