Adding missing `DocumentArray` class.
Adding missing `DocumentArray` class.

davidpersson/lithium,mehlah/lithium,jails/lithium,whowgames/lithium,muyehub/lithium,datachand/lithium,whowgames/lithium,datachand/lithium,qoqa/lithium,UnionOfRAD/framework,pixelcog/lithium,davidpersson/lithium,graphis/lithium,jails/lithium,SensCritique/lithium,UnionOfRAD/lithium,m4rcsch/li3_framework,UnionOfRAD/lithium,wbeater/lithium,pixelcog/lithium,graphis/lithium,SensCritique/lithium,m4rcsch/lithium-core-library,wbeater/lithium,m4rcsch/lithium-core-library,muyehub/lithium,qoqa/lithium,mehlah/lithium