Mobius maze

Randomized maze on [Möbius strip](https://en.wikipedia.org/wiki/M%C3%B6bius_strip). Based on [OpenSCAD 2019.05](http://www.openscad.org/downloads.html).

You can set `angle` to `180 * n` in the .scad file. For example, if you set `angle` to `0`, it's just a circular maze.

[Clean code](https://github.com/JustinSDK/dotSCAD/blob/master/examples/maze/mobius_maze.scad) based on the [dotSCAD](https://github.com/JustinSDK/dotSCAD) library.

include ;
include ;
include ;

rows = 48;
columns = 8;
block_width = 2;
wall_thickness = 1;
angle = 180;
// $fn = 24;

leng = rows * block_width;
radius = 0.5 * leng / PI;
a_step = 360 / leng;

blocks = go_maze(
1, 1, // starting point
starting_maze(rows, columns),
rows, columns, y_circular = true
);
walls = maze_walls(blocks, rows, columns, block_width, bottom_border = false);

for(wall_pts = y_twist(walls, angle, rows, columns, bl