svg.append("rect")
.attr("x", tile.x + padFactor * this.cellWidth * tile.x)
.attr("y", tile.y + padFactor * this.cellWidth * tile.y)
.attr("width", this.cellWidth * tile.width)
.attr("height", this.cellWidth * tile.height)
.attr("fill", "grey")
.attr("class", "tile")
.on("drag", function(){
console.log("dragging");
let t = d3.select(this);
t.attr("x", d3.event.x).attr("y", d3.event.y);
})