router

HTTP router based on radix trees.

Benchmarks

Loading and requesting every single route in github.txt:

BenchmarkLookup-12           	   50715	     23207 ns/op	   11649 B/op	     204 allocs/op
BenchmarkLookupNoAlloc-12    	  148033	      7993 ns/op	       0 B/op	       0 allocs/op