Removing `Session::isValid()`, since it wasn't being used and doesn't very much make sense.
Removing `Session::isValid()`, since it wasn't being used and doesn't very much make sense.

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