Update() callback

[thinsoldier]

On smaller screen sizes I want to change the aspect ratio of the slideshow to be about 1/3 taller. It is possible to change the options.height value and then call update() manually. But when trying to do this in response to a window resize, sometimes my manual height change and call to update happens and then the built in height change and update call happens which overrides my manual call. And other times it happens the other way around and I see my desired change.

It would be more consistent if I could pass a function to be run after every time slidesjs runs its update() function.