getBelow method
Gets the tile immediately to the south (below) of this tile.
Wraps around if at the southern boundary. Returns the southern neighbor tile
Implementation
Tile getBelow() {
int y = tileY + 1;
if (y > getMaxTileNumber(zoomLevel)) {
y = 0;
}
return Tile(tileX, y, zoomLevel, indoorLevel);
}