Fixed
- Give an error message when the user's filters (by level, by topic, by concept identifier) don't match any concepts. Fixes [437](https://github.com/fniessink/toisto/issues/437).
- Give an error message when the target and source language are the same. Fixes [453](https://github.com/fniessink/toisto/issues/453).
- When using the topics command with filters, hide empty topic tables. Fixes [477](https://github.com/fniessink/toisto/issues/477).
Added
- Distinguish between the meanings of questions and answers by inserting a ">" between them. Closes [442](https://github.com/fniessink/toisto/issues/442).
- Warn the user if they are answering in their target language when the source language is asked, or vice versa. Closes [459](https://github.com/fniessink/toisto/issues/459).
- Added quizzes for changing cardinal numbers into ordinals numbers and vice versa.
- Added several topics and concepts.
Changed
- Concepts and topics are now stored in different files. This allows users to create their own topic files consisting of a list of existing topics.
Removed
- Toisto no longer includes CEFR-levels in concept files not uses them sort quizzes. Most if not all sources for CEFR-levels prohibit redistribution of their material. Closes [482](https://github.com/fniessink/toisto/issues/482).