Raise error when unused regular expressions

This prevents typos like (route-compile "/:id" {:is #"\d+"})
Add original path to compiled routes
Remove automatic URL decoding

Changes route parameters so that they're not automatically URL decoded.
This is necessary to reliably support functionality like Compojure's
context macro.
Set project version to 2.0.0-SNAPSHOT
Rename test/core.clj to core_test.clj
Replace custom lexer with Instaparse
Update examples in README
Improve first README example explanation
Release 2.0.0