Merge branch 'gizmo_mfm_clean' into 'master'

examples/SineWavePotential_1D/makeIC.py

examples/SineWavePotential_1D/plotSolution.py

examples/SineWavePotential_1D/sineWavePotential.yml

src/Makefile.am

src/hydro/GizmoMFM/hydro.h

src/hydro/GizmoMFM/hydro_debug.h

src/hydro/GizmoMFM/hydro_gradients.h

src/hydro/GizmoMFM/hydro_gradients_gizmo.h

src/hydro/GizmoMFM/hydro_gradients_sph.h

src/hydro/GizmoMFM/hydro_iact.h

src/hydro/GizmoMFM/hydro_io.h

src/hydro/GizmoMFM/hydro_part.h

src/hydro/GizmoMFM/hydro_slope_limiters_cell.h

src/hydro/GizmoMFM/hydro_slope_limiters_face.h

src/hydro/GizmoMFM/hydro_velocities.h

src/riemann/riemann_hllc.h