Restore entity-to-crewmate conversion trick

So there's this trick that I recently discovered, since many script
commands don't initialize `i` it's possible to use them to manipulate
arbitrary entities by specifying their indice.

This means in 2.2 you can convert entities to pseudo-crewmates by
changing their rule to 6. Except in 2.3, this was fixed when I fixed the
command to work on flipped crewmates as well. So I'm restoring this
functionality, but I recognize the protection that my previous change to
the command did in preventing levels from destroying the player entity
by changing the player's rule to something nonzero, so instead of
removing the if-conditional entirely, I'm making it so that it will only
set the rule if the entity's rule isn't 0.

desktop_version/src/Script.cpp

@@ -1006,7 +1006,7 @@ void scriptclass::run()
 						obj.entities[i].rule = 7;
 						obj.entities[i].tile = 6;
 					}
-					else if (obj.entities[i].rule == 7)
+					else if (obj.entities[i].rule != 0) // Don't destroy player entity (rule 0)
 					{
 						obj.entities[i].rule = 6;
 						obj.entities[i].tile = 0;