- Normalize: https, www or bare host, double slashes and index files,
trailing slash add/remove, optional ASCII lowercasing (defaults change
nothing but scheme, slashes and index files)
- strict URLs through signpost MatchPath: a path that names a record
without being its address 301s to the record's address
- resolve runs normalisation, redirects, strict URLs, then SEO; the
location is the final address, so a visitor makes one hop
- P1 warns when a record's canonical URL redirects
