* Include new icons for toolbar overflow to ensure they are tinted correctly and fit in with the rest of the UI.
* Replace custom code for clearing line edits by including a proper icon for the default action.
Fixes#4407Fixes#4637
Additional changes:
- Fix reference entry colour being incompatible with dark themes
- Fix QWizard page being too bright in dark mode
- Prevent unfocused wheel scroll changes to theme setting