Change constant layout to become circular layout

I'm trying to change the constant layout option to a circular layout which doesn't care about the number of crosses and just arranges the nodes in the form of a circle. The algo I'm using is:

var r = Math.min(this.width, this.height) / 2;

/\* Where to start the circle. */
var dx = this.width / 2;
var dy = this.height / 2;

/\* Calculate the step so that the vertices are equally apart. _/
var step = 2_Math.PI / graph.vertexCount;
var t = 0; // Start at "angle" 0.

for (var i = 0; i

Start by locating VivaGraphJS's constant layout implementation and the graph vertex collection used by the layout. Compare its positioning flow with the supplied circle algorithm; done means vertices are evenly arranged around a circle regardless of the number of crosses and the graph still renders correctly.

Written by the indexing model from the issue text.