Removed hydro_velocities from Makefile.am. Removed some more mass fluxes and...

Removed hydro_velocities from Makefile.am. Removed some more mass fluxes and code that depends on masses changing.

src/Makefile.am

@@ -106,7 +106,6 @@ nobase_noinst_HEADERS = align.h approx_math.h atomic.h barrier.h cycle.h error.h
                  hydro/GizmoMFM/hydro_slope_limiters_face.h \
                  hydro/GizmoMFM/hydro_slope_limiters.h \
                  hydro/GizmoMFM/hydro_unphysical.h \
-                 hydro/GizmoMFM/hydro_velocities.h \
                  hydro/Shadowswift/hydro_debug.h \
                  hydro/Shadowswift/hydro_gradients.h hydro/Shadowswift/hydro.h \
                  hydro/Shadowswift/hydro_iact.h \

src/hydro/GizmoMFM/hydro.h

@@ -614,8 +614,7 @@ __attribute__((always_inline)) INLINE static void hydro_kick_extra(
 
   float a_grav[3];
 
-  /* Update conserved variables. */
-  p->conserved.mass += p->conserved.flux.mass * dt;
+  /* Update conserved variables (note: the mass does not change). */
   p->conserved.momentum[0] += p->conserved.flux.momentum[0] * dt;
   p->conserved.momentum[1] += p->conserved.flux.momentum[1] * dt;
   p->conserved.momentum[2] += p->conserved.flux.momentum[2] * dt;
@@ -665,9 +664,6 @@ __attribute__((always_inline)) INLINE static void hydro_kick_extra(
     a_grav[1] = p->gpart->a_grav[1];
     a_grav[2] = p->gpart->a_grav[2];
 
-    /* Make sure the gpart knows the mass has changed. */
-    p->gpart->mass = p->conserved.mass;
-
     /* Kick the momentum for half a time step */
     /* Note that this also affects the particle movement, as the velocity for
        the particles is set after this. */