v1.4

The package is now available on PyPI, which means that it can just be installed with

pip install normflows

from now on. The code was reformatted to conform to the black coding style.

Moreover, the following fixes and additions are included:

• The computation of the alpha-divergence objective was corrected.
• A bug regarding sampling from the mixture of Gaussian base distribution was fixed.
• A flow layer to warp periodic variables was added.
• The dependency from the Residual Flow repository was removed.