Spiral moving fish

When I published [Moving fish](https://www.thingiverse.com/thing:1702602), someone said: "Could you coil up the fish to allow more segments?"

Coiling up the fish needs [Archimedean spiral](https://openhome.cc/eGossip/OpenSCAD/ArchimedeanSpiral.html) as a base. The original code of [Moving fish](https://www.thingiverse.com/thing:1702602) is quick and dirty so I have to refactor it. The joint between segments also needs some modification. This is a good request. I learned much from it.

You may use [the model with 3 segments](http://www.thingiverse.com/download:2748188) to test your printer. If it's printed successfully, a fish with more segments is basically not a problem.


The number 99 reaches the limit of my 3D printer.

![A fish with 99 segments](http://thingiverse-production-new.s3.amazonaws.com/renders/1f/37/bf/5