Merge branch 'master' into dopair2-vectorisation

configure.ac

examples/main.c

src/cell.c

src/engine.c

src/gravity/Default/gravity_iact.h

src/hydro/DebugInteractions/hydro.h

src/hydro/Shadowswift/hydro_iact.h

src/hydro/Shadowswift/voronoi3d_algorithm.h

src/minmax.h

src/multipole.h

src/runner.c

src/runner_doiact.h

src/runner_doiact_grav.h

src/runner_doiact_vec.c

src/scheduler.h

src/space.c

src/statistics.c

src/timestep.h

tests/test125cells.c

tests/testGravityDerivatives.c