support for ImageSizer, PageImageManipulator, storage of CropRectangleCoords

Hi Antti, here it is :)

We (owzim and me) have tested this very detailed during the last week and it works very well, ... (now, after finding and fixing some minor bugs first,  ;-) )

A explanation and short video is in PW forum:
http://processwire.com/talk/topic/4264-release-page-image-manipulator/page-3#entry42916