WIP on edge cases

Parser is total and can parse easy strings. Still have to nail down some
cases in the RFC, swipe a battery of tests from an existing, mature
parser, benchmarking, etc.
Add initial benchmark scaffolding
Improvements to handling encoded sections of URI

The http-types library had a perfectly good percent-decoder built in
that operated on bytstrings so I decided to use that.
Add Read machinery for errors
Doctest
Documentation