Empty Actor is an actor without any components. It just have a transform and that's it. You are free to attach any component you want to it!
EmptyActor(Vector3D pPos, Vector3D pSize, Quaternion pRotation, ShaderProgram* program);
Call this constructor if you want to spawn an empty actor in the map.
By default the pPos is set to 0, the pSize to 1, the pRotation to 0, the shaderprogram to null (it will use the simpleMeshShaderProgram)