Typing of Polygon.regions as (Vec2 | Vec6)[][] inconvenient

[PaulHax]

Just a quality of life little thing: I updated from v1.1.0 to 2.0.11 and find the region point type changed to a union of Vec2 and Vec6. I added a conversion function to cope:
https://github.com/Kitware/VolView/pull/654/files#diff-ac288c19744025633580fc70a6ad9d7ee58354412af3733088d4ee26a18799c7R22-R31

Would be nice if the type was definitively Vec2 if not using bezier features.