Cannot round trip some query string styles

[Nevett]

MustardBlack.Url changes the query portion of a URI when roundtripping it

e.g.
(new MustardBlack.Url(str)).ToString()

https://www.test.com/?c=foo&b=bar&a=baz becomes https://www.test.com/?a=baz&b=bar&c=foo
https://www.test.com/?a=1&a=2&a=3 becomes https://www.test.com/?a=1%2c2%2c3

This is a problem since MustardBlack.Url is used internally when creating RedirectResults from URL strings, therefore it is not possible to redirect a user to an arbitrary url with confidence it will not be mangled.

Since RFC 3986 offers little specification on the format of query portions of URLs, the safest thing to do would be to preserve whatever is passed in, in scenarios where the Url.QueryCollection is not mutated.

System.Uri handles this use case okay, but is immutable.

[Nevett]

An alternative fix (for the particular problem with redirects) could be to have RedirectResult use System.Uri or just string internally since it doesn't make use of the mutability of MustardBlack.Url