Merge branch 'master' into Self_gravity_BH

examples/plot_tasks.py

examples/plot_tasks_MPI.py

src/Makefile.am

src/engine.c

src/lock.h

src/map.c

src/partition.c

src/queue.c

src/runner.c

src/runner_doiact.h

src/scheduler.c

src/task.c

src/task.h

src/timers.h