Before, modifying the path might have affected how a new query string
was built if the query string relied on the path. Now, we build each
component in isolation and only change the URI on the request later.
Also, prevent trailing & in query string.
Our new parser also preserves original parameter order, rather than
re-encoding using the std lib (which sorts).
The renamed parameters are a breaking change but they're new enough
that I don't think anyone is using them.
