Resizable: Add option for setting the resize center

[acme]

Currently Resizable is using the top left coordinates of the element as resizing center and is resizing to the bottom right.

It would be nice if there was an option to set the resizing center/origin e.g. to the center of the element so it grows to all sides equally.

Sorry, I don't know what's the correct term for "center/origin" in English for describing this feature.

Something like this:

$( ".selector" ).resizable({ origin: 'ne' }); (which is currently the default behaviour

or

$( ".selector" ).resizable({ origin: 'center' });