Unparse should be flexible to unknown implementations

Problem

Unparsing a type, often during unit testing via prn, requires the
type system implementation to be specified. This is too restrictive.

Solution

The unknown implementation should verbosely print types, and ignore
the current namespace.

Notes

Implementation extracted from this branch.

Waiting on: CTYP-256
Pull request: 43
Patch: ctyp-255.patch
Commit: 48c225
Release: 0.3.9