ANKResource::localKeysExcludedFromJSONOutput needs to return an empty set, not nil, so subclasses can add to it
Add mentionMap to ANKEntities:: localKeysExcludedFromJSONOutput
Add parentEntities to ANKEntity:: localKeysExcludedFromJSONOutput
Merge pull request #20 from DaveWoodCom/feature/dw-fix-JSONDictionary-infinite-loop

Feature/dw fix json dictionary infinite loop