Merge branch 'logger_reader' into 'master'

logger/Makefile.am

logger/examples/reader_example.py

logger/gravity/MultiSoftening/logger_gravity.c

logger/gravity/MultiSoftening/logger_gravity.h

logger/hydro/Gadget2/logger_hydro.c

logger/hydro/Gadget2/logger_hydro.h

logger/logger_gravity.h

logger/logger_header.c

logger/logger_header.h

logger/logger_hydro.h

logger/logger_logfile.c

logger/logger_particle.c

logger/logger_particle.h

logger/logger_python_tools.h

logger/logger_python_wrapper.c

logger/logger_reader.c

logger/logger_reader.h

logger/logger_stars.h

logger/logger_time.c

logger/logger_tools.c