Added an imgarrange: option

This will place images in their own column if too large.
Works on images with class "images" appended.

I needed this to make columnizer behave in a predictable fashion in mobile browsers.

I call the function like this:

$('img').addClass('images');
/* set these three classes to img elements, so columnizer v2 can place images in their own column after resizing */
$('#portrait').columnize({ width:vpx,height:vpy,target:'.wide',imgarrange:true });

and now images do not extend below the general column level, and create a new column instead.