Merge branch 'master' into gpart_ids

Conflicts:
	src/debug.c
	src/debug.h
	src/engine.c
	src/gravity/Default/gravity_debug.h
	src/gravity/Default/gravity_part.h
	src/hydro/Gadget2/hydro_debug.h
	src/part.h
	src/runner.c
	src/tools.c
	src/tools.h