struct for URI representation fixes

New branch, changes to pull request #2257
1. Some methods removed.
2. Parsing algorithm changed from regexp to string slicing (by @s-ludwig)
3. proprety "auth" renamed to "userInfo"
4. Examples converted to documented unittests
Please use
```D
import std.algorithm : startsWith;
```
`std.algorithm` is a real module for `startsWith`.