Merge branch 'test27fix' into 'master'

Fix to make test27cells still give 48 neighbours

Small change as test27fix we want to still output the weighted number of neighbours as described by other people.

See merge request !381

tests/test27cells.c

@@ -204,6 +204,10 @@ void zero_particle_fields(struct cell *c) {
 void end_calculation(struct cell *c) {
   for (int pid = 0; pid < c->count; pid++) {
     hydro_end_density(&c->parts[pid]);
+
+    /* Recover the common "Neighbour number" definition */
+    c->parts[pid].density.wcount *= pow_dimension(c->parts[pid].h);
+    c->parts[pid].density.wcount *= kernel_norm;
   }
 }