Merge branch 'master' into updated_vectorisation_tests

examples/main.c

src/cell.c

src/cell.h

src/common_io.c

src/common_io.h

src/engine.c

src/engine.h

src/gravity/Default/gravity_io.h

src/hydro/Default/hydro_io.h

src/hydro/Gadget2/hydro_io.h

src/hydro/Minimal/hydro_io.h

src/parallel_io.c

src/parallel_io.h

src/part.c

src/part.h

src/proxy.c

src/proxy.h

src/queue.c

src/runner.c

src/scheduler.c