message: Use return value rather than out parameter
  Tempting to use an early return within the for loop, though technically
  that would change behaviour if more than one surrounding mine existed.
  Perhaps defer on that idea until later.
diff: @@ -68,7 +68,7 @@ auto myield = std::bind(mine_yield, std::ref(generator));
  // = STATIC/LOCAL FUNCTIONS
  // ===============================================================================
  using TileArray = std::vector<std::vector<std::vector<Tile> > >;
  -static void findSurroundingMineLocation(Point<int>& pt, TileArray& ta)
  +static Point<int> findSurroundingMineLocation(Point<int> pt, TileArray& ta)
  {
  if (ta[0][pt.y()][pt.x()].hasMine())
  {
  @@ -78,12 +78,13 @@ static void findSurroundingMineLocation(Point<int>& pt, TileArray& ta)
  if (ta[0][point.y()][point.x()].hasMine()) { pt = point; }
  }
  }
  + return pt;
  }
  static void addMineSet(Point<int> pt, Point2dList& plist, TileArray& ta, MineProductionRate rate)
  {
  - findSurroundingMineLocation(pt, ta);
  + pt = findSurroundingMineLocation(pt, ta);
  ta[0][pt.y()][pt.x()].pushMine(new Mine(rate));
  ta[0][pt.y()][pt.x()].index(TERRAIN_DOZED);
  