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 l