[cleanup] Removed useless files

include/crocoddyl/multibody/contacts/impulse-3d.hpp

-///////////////////////////////////////////////////////////////////////////////
-// BSD 3-Clause License
-//
-// Copyright (C) 2018-2019, LAAS-CNRS
-// Copyright note valid unless otherwise stated in individual files.
-// All rights reserved.
-///////////////////////////////////////////////////////////////////////////////
-
-#ifndef CROCODDYL_MULTIBODY_CONTACTS_IMPULSE_3D_HPP_
-#define CROCODDYL_MULTIBODY_CONTACTS_IMPULSE_3D_HPP_
-
-// TODO: ImpulseModel3D ImpulseData3D
-
-#endif  // CROCODDYL_MULTIBODY_CONTACTS_IMPULSE_3D_HPP_

include/crocoddyl/multibody/contacts/impulse-6d.hpp

-///////////////////////////////////////////////////////////////////////////////
-// BSD 3-Clause License
-//
-// Copyright (C) 2018-2019, LAAS-CNRS
-// Copyright note valid unless otherwise stated in individual files.
-// All rights reserved.
-///////////////////////////////////////////////////////////////////////////////
-
-#ifndef CROCODDYL_MULTIBODY_CONTACTS_IMPULSE_6D_HPP_
-#define CROCODDYL_MULTIBODY_CONTACTS_IMPULSE_6D_HPP_
-
-// TODO: ImpulseModel6D ImpulseData6D
-
-#endif  // CROCODDYL_MULTIBODY_CONTACTS_IMPULSE_6D_HPP_

include/crocoddyl/multibody/contacts/multiple-impulses.hpp

-///////////////////////////////////////////////////////////////////////////////
-// BSD 3-Clause License
-//
-// Copyright (C) 2018-2019, LAAS-CNRS
-// Copyright note valid unless otherwise stated in individual files.
-// All rights reserved.
-///////////////////////////////////////////////////////////////////////////////
-
-#ifndef CROCODDYL_MULTIBODY_CONTACTS_MULTIPLE_IMPULSES_HPP_
-#define CROCODDYL_MULTIBODY_CONTACTS_MULTIPLE_IMPULSES_HPP_
-
-// TODO: ImpulseModelMultiple ImpulseDataMultiple
-
-#endif  // CROCODDYL_MULTIBODY_CONTACTS_MULTIPLE_IMPULSES_HPP_