Merge branch 'master' into gravity_speedup

.gitignore

examples/main.c

src/active.h

src/cache.h

src/engine.c

src/engine.h

src/hydro/Gadget2/hydro_iact.h

src/kernel_hydro.h

src/runner.c

src/runner_doiact.h

src/runner_doiact_vec.c

src/runner_doiact_vec.h

src/statistics.c

src/statistics.h

src/vector.h

src/xmf.c

tests/Makefile.am

tests/benchmarkInteractions.c

tests/test125cells.c

tests/testInteractions.c