Merge branch 'new_timeline' into star_particles

examples/CoolingBox/coolingBox.yml

examples/CoolingBox/energy_plot.py

examples/CoolingBox/getGlass.sh

examples/CoolingBox/makeIC.py

examples/CoolingBox/run.sh

examples/CoolingBox/test_energy_conservation.py

src/Makefile.am

src/active.h

src/cell.c

src/cell.h

src/cooling/const_du/cooling.h

src/cooling/const_lambda/cooling.h

src/drift.h

src/engine.c

src/engine.h

src/gravity/Default/gravity.h

src/gravity/Default/gravity_debug.h

src/gravity/Default/gravity_part.h

src/hydro/Gadget2/hydro.h

src/hydro/Gadget2/hydro_debug.h