Makeshift vertical alignment

Hello,
Thanks for the great plugin, it is the best solution I have found for my layout. I recently commented on this issue #80: https://github.com/McPants/jquery.shapeshift/issues/80

I have made some modifications to the code in order to implement vertical flow of items; please have a look. I realized after my modifications that I made these changes to the master branch instead of the 3.0, so if you like I can do that, although I am sure you will be able to better optimize than me. I also don't understand the plugin well enough so please suggest improvements as you wish (ex: to isolate this behavior into an option).

Here are a few screenshots to demonstrate the behavior. Note that in some cases (for example the 3 column layout that the third panel went to the first column even though it is better fit in terms of room in the second column -- I do not know how to fix this, so suggestions are welcome)

![4-col](https://f.cloud.github.com/assets/6564897/2059966/bf350746-8bed-11e3-8f56-b259786f6873.PNG)
![3-col](https://f.cloud.github.com/assets/6564897/2059967/bf41742c-8bed-11e3-858e-d6610a2ff68a.PNG)
![2-col](https://f.cloud.github.com/assets/6564897/2059968/bf44f96c-8bed-11e3-8df7-0ab484cc7acb.PNG)

Thanks again for a fantastic plugin