Add mesh extra objects: Update to version 0.3.1

General Pep8 cleanup
Removed unused variables and imports
Removed a panel from add_empty_as_parent
Standardized the property definitions
across all the scripts
Moved scene props from third_domes_panel_271
to init for proper removal
Added a Enum prop for mesh type in teapot
Fixed a small issue with Geodesic domes self.reports
(problem with value fields message spam)
Fixed props names in Geodesic domes
Consistent tooltips
Reorganized menus:
Mechanical Menu including Pipe joints, Mesh gear
Added separators