[Feature Request] Add 'Url' ctor overload that takes 'Uri' as parameter instead of 'string'

[julealgon]

The Url class currently has a single constructor that takes a string instance to create the object.

I think having an overload that takes a Uri would make some usages simpler.

In my particular case, I'm dealing with a Uri value as the base address and the existing API forces me to do a .ToString on it to work with this library.

I believe this is similar to the reasoning in #62 where Uri extension points were requested. IMHO both should be available especially because using raw strings to represent urls in code is a known bad practice and flagged by FxCop and other tools.

[tmenier]

I think this is a good idea. I'm actually thinking about giving System.Uri all the same extension methods that string gets. But that would be a 3.0 thing - this one I can knock off quickly.