- Resolve: do not remove dot segment if a scheme or an authority is present for consistency with parse.

- Resolve: properly normalize relative paths starting with `.` or `..` - Relativize: make use of `.` and do not always use absolute path if there is a candidate relative path containing `/`

Relativize: avoid panic in case of shared UTF-8 prefix

Fixes relativize on IRIs with a scheme and nothing else.

Fixes relative IRI resolution when there is no authority but a path starting with "/".

Adds `Iri::relativize` to build a relative IRI from a base IRI and an absolute IRI.

ipvFuture are now allowed and some characters are now disallowed in some places to follow RFC 3987.