Schemaorg: Mark successorOf/predecessorOf as mutual inverses

[danbri]

• http://schema.org/successorOf
• http://schema.org/predecessorOf

This is vocabulary originally from GoodRelations, and pre-dates our ability to express inverseOf relationships (which means cross-links between the corresponding pages are missing).

[mfhepp]

+1
This is also how it was defined in GoodRelations:
http://www.heppnetz.de/ontologies/goodrelations/v1.html#predecessorOf

[RichardWallis]

Ignore previous commit notice - caused by a typo in a not connected commit elsewhere.

~Richard

[github-actions[bot]]

This issue is being tagged as Stale due to inactivity.