Uri identity for web resources

[dzmitry-lahoda]

typed resources

[andrewlock]

I think the existing Uri type is a better option here

[andrewlock]

I'm very late to this, but the big redesign of the library in this PR is intended to make it easier to add any features you require:

• Fundamental redesign to allow complete customisation #117

The main idea is to make the library much more maintainable while also giving people a mechanism to customise the generated IDs as much as they like. This should make it easy for you to use features like this.