polishing from review

docs/conf.py

docs/examples/howto_meshplotlib/plot_meshplotlib_2d.py

docs/examples/howto_meshplotlib/plot_solid_mechanics.py

docs/examples/howto_propertylib/plot_propertylib.py

ogstools/meshplotlib/core.py

ogstools/meshplotlib/levels.py

ogstools/meshplotlib/plot_features.py

ogstools/propertylib/matrix.py

ogstools/propertylib/mesh_dependent.py

ogstools/propertylib/presets.py

ogstools/propertylib/property.py

ogstools/propertylib/tensor_math.py

ogstools/propertylib/vector.py

pyproject.toml

tests/test_mechanics.py

tests/test_meshplotlib.py

tests/test_propertylib.py