Merge branch 'master' into StefanCooling

examples/plot_scaling_results.py

src/Makefile.am

src/cell.c

src/cell.h

src/debug.c

src/engine.c

src/gravity/Default/gravity.h

src/hydro/Default/hydro.h

src/hydro/Default/hydro_iact.h

src/hydro/Gadget2/hydro_iact.h

src/hydro/Gizmo/hydro.h

src/hydro/Gizmo/hydro_iact.h

src/hydro/Minimal/hydro_iact.h

src/minmax.h

src/partition.c

src/queue.c

src/riemann/riemann_exact.h

src/riemann/riemann_hllc.h

src/runner.c

src/runner_doiact.h