Resizing should be more exposed to the user

[squirrelsquirrel78]

Right now, React Scrollama simply adds Scrollama.handleResize as a resize event to the window. Ideally, users should be able to throttle this resizing. It would also be great to just be able to call it somehow after updating DOM/Step elements.

[frasercrichton]

Hey Jason, is this something you are still working on or has the project been parked? Cheers, Fraser.