Swap rotation while swapping placement

[BensonLaur]

Here is the current mutate function:

SVGnest/svgnest.js

Lines 872 to 894 in 1248dc2

	GeneticAlgorithm.prototype.mutate = function(individual){
	var clone = {placement: individual.placement.slice(0), rotation: individual.rotation.slice(0)};
	for(var i=0; i<clone.placement.length; i++){
	var rand = Math.random();
	if(rand < 0.01*this.config.mutationRate){
	// swap current part with next part
	var j = i+1;
	if(j < clone.placement.length){
	var temp = clone.placement[i];
	clone.placement[i] = clone.placement[j];
	clone.placement[j] = temp;
	}
	}
	rand = Math.random();
	if(rand < 0.01*this.config.mutationRate){
	clone.rotation[i] = this.randomAngle(clone.placement[i]);
	}
	}
	return clone;
	}

When clone.placement[i] and clone.placement[i] are swapped to create an order mutation, I think maybe it is better to also swap the clone.rotation .

For example, if there are two 2 parts called A and B. To put A in the bin, A can not be rotated by 90 degree while B can do this.

This means, the value of clone.rotation[j](B) can be 90 while the value of clone.rotation[i](A) is 0.
In this case, if clone.placement[i] and clone.placement[j] are swapped, and clone.rotation[i] or clone.rotation[j] happens not to be regenerated by this.randomAngle(clone.placement[i]) later, then it would produce an unexpected mutation result.

Although this issue will not happen to small parts data input, I think this change make it more reasonable for big parts input.

Here is the SVG input example mutationExample.zip, if needed, it can be used for test.