message: Remove reference for non-out parameter
  It's not an out parameter, and it's not const. Better to just pass by
  value. The struct is small enough that it should be the fastest way.
diff: @@ -81,7 +81,7 @@ static void findSurroundingMineLocation(Point<int>& pt, TileArray& ta)
  }
  -static void addMineSet(Point<int>& pt, Point2dList& plist, TileArray& ta, MineProductionRate rate)
  +static void addMineSet(Point<int> pt, Point2dList& plist, TileArray& ta, MineProductionRate rate)
  {
  findSurroundingMineLocation(pt, ta);
  