Merge branch 'master' into parco_2019_debug

configure.ac

doc/RTD/source/AnalysisTools/index.rst

examples/main.c

src/Makefile.am

src/engine.c

src/engine_redistribute.c

src/memuse.c

src/memuse_rnodes.c

src/memuse_rnodes.h

src/mpiuse.c

src/mpiuse.h

src/runner_doiact_functions_hydro.h

src/runner_doiact_functions_stars.h

src/runner_doiact_hydro.c

src/runner_ghost.c

src/scheduler.c

src/space.c

src/star_formation/EAGLE/star_formation.h

src/star_formation/EAGLE/star_formation_iact.h

src/star_formation/GEAR/star_formation.h