Fix T51753: Functions expected Polygons in Data

Bump version to 0.1.2
Fix the error with passing objects data that didn't
have at least one polygon to functions expecting them
(like closest_point_on_mesh) added a check for len > 0

Imports as tuples
Consistent prop definitions
Small Pep8 cleanup
Don't use sum as a var name (replaced with sums)
Update wiki link