Wax updates

This contains all the changes for Wax 0.4.0. Things that have changed, generally:

• WaxOverlays were removed (this was done previously by Yash)
• Selection is now being handled differently – this was causing a bug
• CSS for the editor is now coming from wax-prosemirror-core/dist/index.css and wax-prosemirror-services/dist/index.css. This was previously mostly in EditorElements.js.
• Special Characters was reworked. We now have our own custom character list (CharactersList.js); this also broke the differently positioned special characters box in the chat editor.
• onBlur/onChange are no longer part of the Wax component proper; we're using onBlur attached to a div around the Wax component. I'm debouncing the saving (updateManuscript) but not the onBlur.

This fixes what's broken in Wax in the current main branch, but it needs a lot of testing. It is not a perfect fix for the debounce problem; in part this seems to be because the editor component seems to be re-rendering more often than it should be.

(Probably the HiddenTabs merge request should go in before this one, as that resolves a lot of the onBlur issues.)