Merge branch 'experimental' into develop

CMakeLists.txt

core/pymod/CMakeLists.txt

core/pymod/__init__.py

core/pymod/_filecache.py

core/src/enumerator.hh

doc/buildsystem.rst

extras/code_generation/ideal_bb_param.py

extras/data_generation/CONTENT.txt

.../data_generation/rotamer_library/CreateDunbrackLibrary.py

extras/data_generation/rotamer_library/create_penultimate.py

extras/data_generation/rotamer_library/penultimate.csv

...as/fragger_weight_training/fragger_weight_training.tar.gz

loop/doc/structure_db.rst

loop/pymod/_fragger.py

loop/src/CMakeLists.txt

loop/src/backbone.cc

loop/src/bb_trace_param.cc

loop/src/bb_trace_param.hh

loop/src/fragger.cc

loop/src/fragger.hh