Adds UIKit categories

Hi.  A while back you mentioned that you'd be open to having some UIKit stuff which I had been accumulating in my tool chest.  I've begun adding them and will keep doing so provided you approve :)  I commented all the methods but I haven't done tests.  Most of them are a bit tough to unit test though easy to check in practice (e.g. UIImage transformations).  Let me know what you think!  Thanks!  Overline needs much more attention IMHO!