Merge branch 'master' into subset_sorting

.gitignore

configure.ac

doc/Doxyfile.in

src/collectgroup.c

src/runner.c

src/runner_doiact.h

src/runner_doiact_vec.c

src/runner_doiact_vec.h

src/serial_io.c

src/single_io.c

src/tools.c

tests/Makefile.am

tests/difffloat.py

tests/test125cells.c

tests/test27cells.c

tests/test27cells.sh.in

tests/test27cellsPerturbed.sh.in

tests/testPair.c

tests/testPeriodicBC.c

tests/testPeriodicBC.sh.in