Hex maze projection

It's based on [Hex maze pyramid](https://www.thingiverse.com/thing:1862127) and the `stereographic_projection` in [my stereographic things](https://www.thingiverse.com/JustinSDK/collections/stereographic-projection).

It doesn't matter that the hex maze is not a square. Actually, all kind of shapes can be projected.

Find my things about stereographic projection in [stereographic_projection](https://www.thingiverse.com/JustinSDK/collections/stereographic-projection).

Find all my mazes in the collection "[maze generators](http://www.thingiverse.com/JustinSDK/collections/maze-generator)".

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- *[OpenSCAD Documentation - Traditional Chinese](http://openhome.cc/Gossip/OpenSCAD/)*
- *[OpenSCAD Documentation - English](http://openhome.cc/eGossip/OpenSCAD/)*

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