v5.6.0-beta.0

What's Changed

• Refactor math by @ikatson in #108
• Ability to change selected files after adding the torrent by @ikatson in #109

There's a lot of internal changes to the math in attempt to make it simpler to understand and to work with. Also a bunch of tests.
But as there's many changes, it could bring new bugs. So marking beta for now.

Full Changelog: v5.5.4...v5.6.0-beta.0