Towards pysteps v2.0

[sidekock]

With the progress on the xarray integration into pysteps well on the way, it is time to start to think about additional features/breaking changes/deprecated parts of the project we want to tackle at the same time. Please leave suggestions for these sorts of changes below so they can be discussed.

[dnerini]

we had some open issues that would fit well in V2, looking also at this older thread #216:

• Use logging instead of print #140
• Migrate static metadata to pyproject.toml for improved packaging standards #487
• install optional dependencies with extras
• change the pystepsrc parameter file format to YAML format
• ...