[Client] Mark trivial destructor as default, remove "virtual" keyword

Mark constructor as explicit

apps/openmw/mwmp/Cell.cpp

@@ -27,11 +27,6 @@ mwmp::Cell::Cell(MWWorld::CellStore* cellStore)
     updateTimer = 0;
 }
 
-Cell::~Cell()
-{
-
-}
-
 void Cell::updateLocal(bool forceUpdate)
 {
     if (localActors.empty())

apps/openmw/mwmp/Cell.hpp

@@ -12,8 +12,8 @@ namespace mwmp
     {
     public:
 
-        Cell(MWWorld::CellStore* cellStore);
+        explicit Cell(MWWorld::CellStore* cellStore);
-        virtual ~Cell();
+        ~Cell() = default;
 
         void updateLocal(bool forceUpdate);
         void updateDedicated(float dt);