Reevaluate table and header position and height when needed

[HarlemSquirrel]

This helps with dom changes such as showing/hiding an element or filtering a table and with window resizing.

• Move table and header position and size evaluation to function
• Reevaluate on page resize
• Reevalute on scroll if the body height has changed

[HarlemSquirrel]

Thanks for your awesome library! I thought you might like this small addition I'm using for a page that changes as the user filters the table or hides/reveals some elements.