Simplify default return value of loadcases dof.uniaxial(), dof.shear() and dof.biaxial()

[adtzlr]

Changed

• Change the default output of the loadcases dof.uniaxial(), dof.shear() and dof.biaxial() to only return the dict of boundary conditions boundaries = fem.dof.uniaxial(field) (was boundaries, loadcase = fem.dof.uniaxial(field) before). The additional loadcase dict is now optional, boundaries, loadcase = fem.dof.uniaxial(field, return_loadcase=True). Note that this is a non backward compatible change.

Deprecated

• Deprecate bounds in dof.symmetry(field, bounds=None). Use new equivalent boundaries argument, dof.symmetry(field, boundaries=None).

This change is useful because the loadcase dict isn't required in typical high-level scripts anymore. This will make the high-level code snippets much clearer as the unused loadcase dict won't be visible.

This PR also removes the deprecated SolidBodyGravity.

closes #1021

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 97.40%. Comparing base (4eb92b8) to head (a402fa7).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1022   +/-   ##
=======================================
  Coverage   97.39%   97.40%           
=======================================
  Files         185      184    -1     
  Lines        7031     7015   -16     
=======================================
- Hits         6848     6833   -15     
+ Misses        183      182    -1     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.