Create js Sets using arrays

The .add() function of Set is much slower than .push of an array. See this [post](https://stackoverflow.com/questions/39007637/javascript-set-vs-array-performance) for more details.

I also created simple test to verify and it seems creating an array and then converting it to a set is much faster than just using set.add(). In the below example, 'add by set' takes ~4 seconds will 'add by index' takes ~0.5 seconds. So, if we initialize all sets using arrays, we can save a significant amount of time. This would be especially helpful for the coloring/bar plot methods. Note: we still want to use sets because .has is much faster than indexOf.

```
var f = function() {
var t = [];
var d = new Date();
for (var i = 0; i < 10000000; i ++) {
t[i] = 1;
}
var st = new Set(t);
st.has(1) ? console.log("!!!") : console.log(":(");
var dt = new Date();
console.log("add by index", dt.getTime() - d.getTime());

var t = [];
var d = new Date();
for (var i = 0; i < 10000000; i ++) {
t.push(i)
}
var st = new Set(t);
st.has(1) ? console.log("!!!") : console.log(":(");
var dt = new Date();
console.log("add by push", dt.getTime() - d.getTime());

var t = new Set();
var d = new Date();
for (var i = 0; i < 10000000; i ++) {
t.add(i);
}
var dt = new Date();
console.log("add by set", dt.getTime() - d.getTime());

var d = new Date();
var t = new Array(10000000);
for (var i = 0; i < 10000000; i ++) {
t[i] = 1;
}
var st = new Set(t);
st.has(1) ? console.log("!!!") : console.log(":(");
var dt = new Date();
console.log("add by init", dt.getTime() - d.getTime());

var d = new Date();
var t = new Array(10000000).fill(0);
for (var i = 0; i < 10000000; i ++) {
t[i] = 1;
}
var st = new Set(t);
st.has(1) ? console.log("!!!") : console.log(":(");
var dt = new Date();
console.log("add by init and fill", dt.getTime() - d.getTime());
}
f();
```