Change load_array() -> load_layers(), return xr.Dataset

[gbrener]

Addresses #31 by changing load_array() to load_layers(), and having the function return an xr.Dataset object instead of MLDataset.

[PeterDSteinberg]

One variable naming thing related to this PR:

• Change the usage of es (formerly an ElmStore from Phase I approach) to dset. There may also be places where X is used and dset would be more consistent with xarray/xarray_filters naming.

[gbrener]

@PeterDSteinberg, just made the es -> dset change. Wasn't able to find X being used anywhere, but I could've missed something.

[PeterDSteinberg]

Searching shows just one docstring using X:

earthio/earthio/tif.py

Line 168 in 8ac7273

:X: xr.Dataset

here where :X: should be :dset:

[PeterDSteinberg]

Otherwise - can merge when tests pass.

[gbrener]

Ah, thanks for pointing that one out. Just pushed up the fixes; waiting on tests to pass.

[PeterDSteinberg]

With changes in the environment.yml / conda.recipe, can this line now be removed from build_earthio_env.sh?

[gbrener]

Yes, I believe so - just pushed up the change.

[gbrener]

Merged despite package upload failure - that issue will be addressed in a separate PR.