Features/tweaks:
- Show term popup if term has tag.
- #525: add Save Term customizable hotkey.
- #517: show page fraction even if book completed.
- #524: show popup for terms with data, ignoring status.
- #522: allow term import with identical lines.
- Update arabic language definition.
Back end changes:
- use pyproject.toml and flit only for managing dependencies
- #534: change how Lute loads demo data for new installs