- Refactored Tekstowo backend to fetch lyrics directly from song pages.
- Added `encode` method to convert artist and title to their URL format,
where non-alphanumeric characters are replaced with underscores.
- Removed the now redundant search functionality and associated tests.
- Simplified `extract_lyrics` method to directly parse lyrics without
any checks.
External Python packages interfacing beets may want to use an in-memory
beets library instance for testing beets-related code.
The `TestHelper` class is very helpful for this purpose.
Previously `TestHelper` was located in the `test/` directory.
Now it is part of `beets` itself (`beets.test.helper.TestHelper`) and
can be easily imported.