Add ability to box the dimensions

[tdillon]

Add a setter that will fit the size of the Seven inside the specified dimensions. The setter is named box and it accepts an object with the shape { height:number, width:number }. Either the height or the width of the digit will be the corresponding value from the box property, the other will be less than its corresponding value.

var x = new Seven({angle: 0});
x.box = { height: 100, width: 75 };  //height === 100, width < 75;
x.angle = 70;  //height < 100, width === 75, 

Setting height or width overrides the box property.