Duplo Gears, now with snap rotation!

The script recreates the Duplo Gears [26832](https://brickset.com/parts/design-26832) (6167506, 6167507, 6175006) and [26835](https://brickset.com/parts/design-26835) (6167508). It also generates more sizes of matching gear wheels as well as a part to lock the wheels in place from the top for improved stability of more complex creations.

New in 2019:
* Now each gear has a rotation joint so it can be connected to a standard Duplo snap rotation joint. Official parts: [92005](https://brickset.c