Small offset at meeting of some elements

[Hasan Edain]

In the following code, if you examine where the square elements meet the round elements, you will notice a small "jog" (see attached screenshot).

If you have a notion where I could fix this, I would gladly make a PR to adjust.
I am contemplating using this with the "projection()" command to export SVG files for LaserCutting use.
The small "Jogs" will cause the laser head to spend longer in that spot than other portions of the line, and as a result will have a darker spot there.
Thanks so much for making a cool library.

`use <celtic-knots.scad>

tileSize = 100;
spacer = 3 * tileSize;

translate([0,0,0]) {
knot( [ "<>",
"[];" ], tile_width = tileSize);
}

translate([spacer,0,0]) {
knot( [ ",.",
"{}" ], tile_width = tileSize);
}

translate([0,spacer,0]) {
knot( [ "<>",
"[};" ], tile_width = tileSize);
}

translate([spacer,spacer,0]) {
knot( [ ",.",
"{]" ], tile_width = tileSize);
}`