Descriptors to manage which atoms to calculate

include/tadah/models/descriptors/d2/d2_base.h

include/tadah/models/descriptors/d3/d3_base.h

include/tadah/models/descriptors/d_base.h

include/tadah/models/descriptors/dm/dm_base.h

include/tadah/models/descriptors/dm/dm_mEAD.hpp

src/d2_base.cpp

src/d2_blip.cpp

src/d2_bp.cpp

src/d2_eam.cpp

src/d2_lj.cpp

src/d2_mie.cpp

src/d2_zbl.cpp

src/d3_base.cpp

src/d_base.cpp

src/d_mjoin.cpp

src/dm_base.cpp

src/dm_blip.cpp

src/dm_ead.cpp

src/dm_eam.cpp