Echoes when there shouldn't be

[Pixelfest]

Commandline with "-d Circles.png -p TestPattern.png" generates an image with small echoes. I think this can be fixed.

[Pixelfest]

// Code is it is now
var left = x - separation / 2;
var right = left + separation;

// This misalignes from the center, but everything on the left is echo-less! Echoes are worse on the right.
var left = x - separation;
var right = x;