added functionity to lib interface

doc/src/Section_howto.txt

src/KSPACE/ewald_disp.cpp

src/REPLICA/prd.cpp

src/RIGID/compute_rigid_local.cpp

src/RIGID/compute_rigid_local.h

src/compute.cpp

src/compute_angle_local.cpp

src/compute_angle_local.h

src/compute_bond_local.cpp

src/compute_bond_local.h

src/compute_dihedral_local.cpp

src/compute_dihedral_local.h

src/compute_gyration_chunk.cpp

src/compute_improper_local.cpp

src/compute_improper_local.h

src/compute_pair_local.cpp

src/compute_pair_local.h

src/compute_property_atom.cpp

src/compute_property_local.cpp

src/compute_property_local.h