Merge branch 'release-2.1.0'

CHANGELOG

CMakeLists.txt

cmake_support/PROMOD3.cmake

container/Dockerfile

core/src/eigen_types.hh

core/src/superpose.cc

core/src/superpose.hh

core/src/tetrahedral_polytope.cc

core/src/tetrahedral_polytope.hh

core/tests/test_check_io.cc

core/tests/test_graph_minimizer.cc

core/tests/test_portable_binary.cc

core/tests/tests.cc

doc/buildsystem.rst

doc/conf.py.in

doc/container/singularity.rst

doc/html/_sources/buildsystem.txt

doc/html/_sources/changelog.txt

doc/html/_sources/container/singularity.txt

doc/html/_sources/loop/backbone.txt