Animate: Animate page element updating a given style value

This object can animate a page element by updating a style value progressively.

It takes a given page element and retrieves the current value of a given numeric style value.

The object repeatedly updates the value of the style value until it reaches a given final value.

The calculation of each new value of the element style can be defined by different functions of a separate object. Different types of functions are provided to implement several levels of animation smoothness.

The time interval between the start and the end of the animation is a configurable parameter.

The object can invoke given callback functions every time the page element style value is updated, as well when the animation is completed.