Automatic upgrade of dead link relations

[simongray]

See e.g. rdfs:isDefinedBy in http://localhost:3456/dannet/external/svs/term_status

The linked resource ends in # and this doesn't resolve to anything. However, removing the # and retrying the fetch does. One could argue that a URI with an empty # (= empty fragment string) is in fact the same as one without a # at all, so upgrading to the resource without the # at the query level should be entirely legal. However, for the odd case where the #-appended resource identifier actually resolves to something we want to return that entity instead.

It should be implemented as a basic dual search, but only in cases where the resource identifier matches this pattern and nothing is found on the first attempt.