Update addon to Blender 2.8

add_mesh_extra_objects/__init__.py

add_mesh_extra_objects/add_mesh_beam_builder.py

add_mesh_extra_objects/add_mesh_gears.py

add_mesh_extra_objects/add_mesh_gemstones.py

add_mesh_extra_objects/add_mesh_honeycomb.py

add_mesh_extra_objects/add_mesh_menger_sponge.py

add_mesh_extra_objects/add_mesh_pyramid.py

add_mesh_extra_objects/add_mesh_round_brilliant.py

add_mesh_extra_objects/add_mesh_star.py

add_mesh_extra_objects/add_mesh_twisted_torus.py

add_mesh_extra_objects/add_mesh_vertex.py

add_mesh_extra_objects/geodesic_domes/__init__.py

...esh_extra_objects/geodesic_domes/third_domes_panel_271.py

add_mesh_extra_objects/mesh_discombobulator.py