call doPhysics function once per frame

apps/openmw/engine.cpp

@@ -179,6 +179,8 @@ bool OMW::Engine::frameStarted(const Ogre::FrameEvent& evt)
 
             focusFrameCounter = 0;
         }
+
+        mEnvironment.mWorld->doPhysics (mEnvironment.mFrameDuration);
     }
     catch (const std::exception& e)
     {

apps/openmw/mwworld/world.cpp

@@ -833,4 +833,9 @@ namespace MWWorld
         if (y<0)
             --cellY;
     }
+
+    void World::doPhysics (float duration)
+    {
+        mScene.doPhysics (duration, *this);
+    }
 }

apps/openmw/mwworld/world.hpp

@@ -162,6 +162,9 @@ namespace MWWorld
 
             void positionToIndex (float x, float y, int &cellX, int &cellY) const;
             ///< Convert position to cell numbers
+
+            void doPhysics (float duration);
+            ///< Run physics simulation and modify \a world accordingly.
     };
 }