Provide automated fixes for SKOS inputs

[tfrancart]

Similar to what Skosify does : https://github.com/NatLibFi/Skosify/wiki/Validation
Possible fixes are :

• Generate skos:broader/skos:narrower inverses
• Delete empty labels
• Generate skos:related as symetric properties
• Delete skos:related when redundant with skos:broader/narrower
• Remove extra whitespaces or non-printable characters in the labels
• Keep only one prefLabel per language and save the others as altLabels (warniing : handle SKOS-XL !)
• Remove overlapping labels
• Cut the cycles in the hierarchy
• Automatically add documentation properties based on the Concept URI and/or label
• Remove the topConceptOf pointing to Concepts having broaders
• Delete all triples with "Undefined SKOS resources"

[nicholascar]

Just make sure the automated fixes are optional! Some time people may want you to 'fix everything' (as much as the tool can) but other times they just want the qSKOS info in order to make fixes to their system themselves.