Major Deprecation Removal of modules for v2.0.0

[jbusecke]

I am planning to deprecate/retire many of the modules in xarrayutils for an upcoming major release v2.0.0.

As far as I know the following modules have been entirely superseded by other packages:

• visualization.py: xmovie
• vertical_coordinates.py/vertical_remapping.py : xgcm.transform
• weighted_operations.py: xarray.weighted (Deprecate weighted_operations.py #82)
• numpy_utils.py: This badly named module should be completely covered by xESMF at this point.

I will remove these modules for the next minor release. I am not sure if this will break people workflow (if so please let me know below).
I am wondering if I should just remove them or add a deprecation warning? For now that seems excessive, but if you think otherwise, again let me know.

Some other modules are partially integrated into other packages, but some things should still be ported.

• xmitgcm_utils.py/xgcm_utils.py/build_grids.py: Some of the functionality is already ported to xgcm, but there are still things that I would have to generalize and add to xgcm.

I will see if I have the time to migrate these fully for v0.2.0, otherwise this will be done for the next minor release.