v3.1-beta4

New in 3.1 so far:

• Improved performance by testing with large amounts of datasets.
• Optimized performance by making --no-holds also not use holds on the target. (this is also more like expected behavior)
• Fixed --ignore-transfer-errors
• Added --no-thinning option. fixes #54
• Proper ZFS encryption support: https://github.com/psy0rz/zfs_autobackup#how-zfs-autobackup-handles-encryption
• Various fixes and improvements

Internal/development changes:

• Split up classes into separate modules. Direct download no longer supported. (Use pip or easy_install from now on)
• Huge cleanup of codestyle and other linter warnings. should be no functional changes.
• Cleaned up git repository
• Moved regression testing from Travis-CI to github actions.
• Build and upload python package via github actions.
• Cleaned-up and improved select-code.
• Restructured pipe-handling via CmdPipe

Misc:

• Fixed beta1 progress regression.
• Fixed beta3 --ignore-transfer-errors regression.