EZP-20530: tested Content after updating ContentType
Fixed: coverter sets field definition default value sort key
EZP-20530: added listVersionNumbers(), removed second param from deleteField()
Fixed: PHPDoc CS
EZP-20530: add action adds field to all content versions
Resolved todo: external data is handled
EZP-20530: remove action removes field from all content versions
Updated: isolate id cache under own key
EZP-20530: fixed two instances being created for circular dependencies