start filling up testing suite & docstrings

[jGaboardi]

start filling up testing suite – break out to appropriate PRs

• artifacts.py
  • document & refactor artifacts.get_artifacts() #103
  • doc work + type hints in artifacts.py [part 1] #109
  • doc work + type hints in artifacts.one_remaining_c() #114
  • doc work + type hints in artifact.multiple_remaining(), etc. #115
• continuity.py
  • dedicated minimal tests for continuity.py #50
• geometry.py
  • testing for geometry.angle_between_two_lines() #24
  • first round geometry.voronoi_skeleton() tests #27
  • chip away some refactors in geometry.py #46
  • full coverage for geometry.py with minimal tests #53
• nodes.py
  • dedicated minimal tests -- nodes.split() #55
  • dedicated minimal tests -- nodes.get_components() #57
  • dedicated minimal tests -- nodes.weld_edges() #58
  • dedicated minimal tests -- nodes.remove_false_nodes() #59
  • dedicated minimal tests -- nodes.induce_nodes() #67
  • tweaking loop logic for node induction #79
  • granular test for nodes.fix_topology() #91
  • testing and small refactor -- nodes.consolidate_nodes() #97
  • Remove faulty condition in nodes._status() #98
• simplify.py
  • small integrated testing data - apalachicola, fl #29
  • full fua testing for simplify_network() #41
  • docstring & typehints in simplify.network_simplify(), etc. #107
  • docstring & typehints in simplify.simplify_loop(), etc. #112
  • docstring & typehints in simplify.simplify_singletons(), etc. #113
  • ...
  • ...

should get a good base of individual tests (make sure individual case results) before starting with integrated cases (to ensure cases don't break each other).

xref #7