anchor.diff:  {Mark previous tile as empty and next one as occupied}
   procedure TTerrain.UnitWalk(LocFrom,LocTo:TKMPoint);
   begin
  -  //@Lewin: Still occasional Errors here, sometimes during fights
  -  //@Lewin: Mission6 TSK, do no actions, just watch, shows an error here
  -  //@Krom: Thanks for the report, but I can't reproduce it :( I'm using SR3 B7 mission files. Can you send me a save please? I'd really like to fix this bug.
     if not DO_UNIT_INTERACTION then exit;
     dec(Land[LocFrom.Y,LocFrom.X].IsUnit);
     inc(Land[LocTo.Y,LocTo.X].IsUnit);
  
positive.code:       if KMSamePoint(L1.List[i],Loc2) then Loc2IsOk := true; //Make sure unit that pushed us is a valid tile
        TempUnit := fPlayers.UnitsHitTest(L1.List[i].X, L1.List[i].Y);
        if TempUnit <> nil then
          if ((TempUnit.GetUnitAction is TUnitActionStay) and (TempUnit.GetUnitActionType = ua_Walk) and (not TUnitActionStay(TempUnit.GetUnitAction).Locked) then
            L3.AddEntry(L1.List[i]);
      end;
  
  
negative.code: procedure TTerrain.UnitAdd(LocTo:TKMPoint);
  begin
    if not DO_UNIT_INTERACTION then exit;
    inc(Land[LocTo.Y,LocTo.X].IsUnit);
  end;
  
  