Updated mediawiki/extensions
Project: mediawiki/extensions/Flow  013b7c48e15f833e16c16f2ea733c2fccb3c8954

Implement ManagerGroup::clear

Adds a ManagerGroup helper for ObjectManager::clear to simplify
clearing multiple managers.

Change-Id: I04feebe2e83f9e376fe5e5a13b404ca5605ec269