Bump sidechain module to (c) 2020

doc/conf.py.in

...ta_generation/all_atom_scorer/create_default_aa_scorer.py

modelling/pymod/export_motif_finder.cc

modelling/src/motif_finder.cc

modelling/src/motif_finder.hh

sidechain/data/convert_lib.py

sidechain/doc/disulfid.rst

sidechain/doc/frame.rst

sidechain/doc/graph.rst

sidechain/doc/index.rst

sidechain/doc/loading.rst

sidechain/doc/rotamer.rst

sidechain/doc/rotamer_constructor.rst

sidechain/doc/rotamer_lib.rst

sidechain/doc/subrotamer_optimizer.rst

sidechain/pymod/__init__.py

sidechain/pymod/export_connector.cc

sidechain/pymod/export_disulfid.cc

sidechain/pymod/export_frame.cc

sidechain/pymod/export_particle.cc