Fix updating of vertex normals for animated meshes (#77)

Updates cached positions and normals of animated vertices
from the mesh. Useful when using meshManipulator to update
the normals.

source/Irrlicht/CSkinnedMesh.h

@@ -113,6 +113,9 @@ namespace scene
 		//! (This feature is not implemented in irrlicht yet)
 		virtual bool setHardwareSkinning(bool on) _IRR_OVERRIDE_;
 
+		//! Refreshes vertex data cached in joints such as positions and normals
+		virtual void refreshJointCache() _IRR_OVERRIDE_;
+
 		//Interface for the mesh loaders (finalize should lock these functions, and they should have some prefix like loader_
 		//these functions will use the needed arrays, set values, etc to help the loaders