CPCollectionView -maxItemSize support, content binding, collection view item loading ... [+4]

Includes:
• CPContentBinding support. it was there but unusable due to a late minItemSize update.
• CPCollectionViewItem can be loaded from an external cib. You can now have outlets and bindings from/to the prototype. They will be automatically connected for each item in the collection view.
• Support for maxitemSize width and height, including zero width/height interpreted as fully sizable.

The layout is now left-based which is the default in cocoa. But our current layout with centered views is also fine. You can switch back to it with the -uniformResizing flag. (It's just a bit more costly because we need to relayout more often).

With manual test of course.