Fixed versions in develop mode; Module docstrings; More Env Improvements

[aufdenkampe]

This PR:

• Fixes the version attribute import error when in conda develop mode, while also preserving the versioning for packaging. It does so by moving the code from _version.py into the main init file. Thanks @ptomasula for helping me work through this "cake-and-eat-it-too" approach!
• Adds module-level docstrings.
• Updates environment files to follow conventions (i.e. putting Python version at top; put env managment at the bottom).
• Changed default environment name to hsp2 and unconstrained Python to >=3.10.

In my test of these updates to environment.yml, conda installed Python 3.12.8, and everything worked well.

• NOTE that 3.12 became the default with Anaconda 2024.06-1 (Jun 26, 2024), so all major scientific Python packages support it.
  • Python 3.12 is faster than Python 3.10. In my quick comparison, it was about a 10-15% speedup, but it can be up to 2x faster in some cases (see https://medium.com/@spraneeth4/from-python-3-10-to-3-12-specializing-adaptive-interpreter-delivers-real-world-performance-57b7712dbb97)

cc: @timcera

[timcera]

Nice!

[PaulDudaRESPEC]

This looks good!