Namespace: explicit parsing errors

This PR requires the parser to throw an error if a (percent-encoded) solidus `/` is encountered in any path segment.

Signed-off-by: Piotr P. Karwasz <[email protected]>

Author: ppkarwasz

PURL-SPECIFICATION.rst

@@ -415,6 +415,7 @@ To parse a ``purl`` string in its components:
   - Discard any empty segment from that split
   - Percent-decode each segment
   - UTF-8-decode each segment if needed in your programming language
+  - Signal an error if any segment contains a solidus `/`
   - Apply type-specific normalization to each segment if needed
   - Join segments back with a '/'
   - This is the ``namespace``