added ResizeCallback to ResizeSensor.d.ts and added static functions …

[coalman]

…to ResizeSensor class

This adds a ResizeCallback type instead of Function and adds the static detach/reset functions to ResizeSensor.

This allows the following:

const callback: ResizeSensorCallback = (size) => {
  console.log(size.width); // size.width is a number
  console.log(size.height); // size.height is a number
};

const sensor = new ResizeSensor(element, callback);
ResizeSensor.detach(element, callback); // type checked args
ResizeSensor.reset(element); // type checked args
sensor.detach(callback); // type checked arg
sensor.reset(); // type checked

[marcj]

Cool thanks!