SERVER-7174 Minor cleanups for $bit
SERVER-7174 Fix a minor issue with mutables checkDoc
SERVER-7174 Only validate sign direction on document mismatches
SERVER-7174 Add a new algorithm to de-duplicate children
SERVER-7174 Add support for $addToSet on new update framework
SERVER-7174 Add support for $pull on new update framework
SERVER-9750 Fix BSONObj::toString handling of empty arrays