Class iterators

[PMeira]

Extensive changes:

• migrate to classes
• add support for multiple DSSContexts
• use more enums
• update documentation in general, and migrate to MyST and autodoc2 (required some monkey-patching for the time being) -- docs are fully Markdown now, including docstrings
• migrate to PyProject.toml, with hatchling and versioningit instead of setuptools
• add NumPy support; although installing Pandas already installs NumPy, and optionally SciPy, we added

Closes #55, closes #56, closes #60, closes #70, closes #103.

[PMeira]

At the moment this would work for most classes:

I need to test some other things to be sure everything planned in #55 can be done without issues.

[PMeira]

In [1]: from opendssdirect import Loads

In [2]: import opendssdirect as odd

In [3]: odd.Text.Command('redirect ../electricdss-tst/Distrib/EPRITestCircuits/ckt5/Master_ckt5.dss')

In [4]: len(Loads)
Out[4]: 1379

In [5]: from opendssdirect.Loads import Name

In [6]: Name()
Out[6]: 'mdv201_hn_2_133_abc8083-1a3'

This current version is almost there. The only change in the tests was changing the asserts for modules, since they're not anymore in the final names. The modules still exist though (as shown in from opendssdirect.Loads import Name), so we should be safe if users imported only parts.

A few modules like YMatrix and Monitors will still be migrated. After that, we can introduce DSS contexts without too much hassle.

[PMeira]

Still needs some final clean-up (some __slots__ shouldn't exist) and some work from #103 could be merged too (especially updated tests).

The docs seem to be generated without issues already, I thought it would need more work.

[PMeira]

I have to rebase, document and update this. After that, this should be v0.9.0

[PMeira]

Remaining steps:

• implement toggling ndarray vs list (that's why some of the tests are failing), per Use environment variable for numpy version #103
• decide (added) if we want to toggle complex and shaped arrays too (the DSS.AdvancedTypes in DSS-Python).
  • needs tests
• check/test some third-party modules that use ODD.py to see what issues users can expect
  • try to work around the most common issues
  • DiTTo
  • PyDSS
• add DSSContexts
  • needs a test (can port from DSS-Python)
  • and at least a link to the finished version of https://github.com/dss-extensions/dss-extensions/blob/main/multithreading.md
• update the docs/tests/examples to use the new iterators

[PMeira]

• For DiTTo, the only mandatory change was actually related to the property naming styles, which isn't directly related to this PR but the changes in DSS C-API.

This will enough to handle that (needs latest commits here and from DSS-Python):

from opendssdirect import dss, enums as dss_enums
dss.Settings.SetPropertyNameStyle(dss_enums.DSSPropertyNameStyle.Legacy)

• For PyDSS, I posted a comment here: PyDSS is incompatible with OpenDSSDirect.py v0.8.1 NREL/PyDSS#121 (comment) -- besides the Legacy thing above, a couple of trivial changes are required for tests to pass.