Round Duplo Column

Part of the [Duplo Gears Project](https://www.thingiverse.com/thing:2268803) but can be useful independent from it.

The script recreates the round Duplo column used in the Duplo Gears sets to make the gears run more stably. Columns of any height can be generated. Approximating Duplo design [98225](https://brickset.com/parts/design-98225) (6021304, 4644209, 6033052, 6056591, 6058761, 6096680, 6022357, 72219).

Also supported are special nibbles to lock to the bottom of the gears to enable locking gears together on an axis. For more flexibility, this works at 45 degree angles. Use a minimum Duplo height of 2 when using lock nibbles or you will have difficulties getting them out of your gears again.

Now updated:
* Contains [Duplo Technic axle](https://www.thingiverse.com/thing:3416238) hole
* Bottom center hole diameter fixed to support connecting to big center stud
* Script also generates [Duplo Snap Rotation Joint male parts](https://www.thingiverse.com/thing:3329573).