Merge branch 'use_class' into 'use_boost'

Jenkinsfile

configure.ac

src/Makefile.am

src/csds_cache.hpp

src/csds_clocks.cpp

src/csds_clocks.hpp

src/csds_cosmology.cpp

src/csds_cycle.hpp

src/csds_error.hpp

src/csds_fields.hpp

src/csds_hashmap.cpp

src/csds_hashmap.hpp

src/csds_header.cpp

src/csds_header.hpp

src/csds_index.cpp

src/csds_index.hpp

src/csds_interpolation.hpp

src/csds_logfile.cpp

src/csds_logfile.hpp

src/csds_mapped_file.cpp