a bunch of fixes and breaking changes

[kthyng]

• updating versioning approach
• the xgcm grid is no longer attached to every variable in a Dataset. Because of this:
  • Several xroms accessor functions now require the grid to be input
  • Additionally because of the grid not being available, the Dataset is no longer available within the DataArray accessor, making it so that functions that change the grid size in any dimension no longer know about other coordinates to use. Therefore, these xroms accessor functions for DataArrays no longer work (e.g. ddeta, ddxi, etc). All xroms Dataset accessor functions still work, and the grid object is still saved to the Dataset xroms accessor.
• You can set up the grid object directly in your xroms Dataset accessor with ds.xroms.set_grid(grid), otherwise it will be calculated internally.
• xroms functions for opening model output files will be deprecated in the future; use xarray functions directly instead of opening model output through xroms, and then run xroms.roms_dataset() to add functionality to your Dataset and to calculate your xgcm grid object.
• tests have been updated
• xroms works with newest version of xgcm

[codecov-commenter]

Codecov Report

Merging #40 (0a6647d) into main (9778c5c) will decrease coverage by 5.62%. The diff coverage is 60.00%.

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@@            Coverage Diff             @@
##             main      #40      +/-   ##
==========================================
- Coverage   93.90%   88.29%   -5.62%     
==========================================
  Files          14       14              
  Lines        1723     1700      -23     
==========================================
- Hits         1618     1501     -117     
- Misses        105      199      +94     

Flag	Coverage Δ
unittests	88.29% <60.00%> (-5.62%)	:arrow_down:

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
xroms/tests/test_xroms.py	100.00% <ø> (ø)
xroms/utilities.py	94.44% <ø> (ø)
xroms/xroms.py	59.70% <48.45%> (-29.02%)	:arrow_down:
xroms/__init__.py	78.57% <50.00%> (ø)
xroms/accessor.py	89.50% <88.23%> (-7.61%)	:arrow_down:
xroms/interp.py	54.32% <100.00%> (-1.24%)	:arrow_down:
xroms/roms_seawater.py	95.68% <100.00%> (-0.08%)	:arrow_down:
xroms/tests/test_accessor.py	99.04% <100.00%> (-0.06%)	:arrow_down:
xroms/tests/test_interp.py	76.31% <100.00%> (ø)
xroms/tests/test_roms_seawater.py	100.00% <100.00%> (ø)
... and 1 more