code: public void setTileId(int x, int y, int layerIndex, int tileid) {
  		Layer layer = (Layer) layers.get(layerIndex);
  		layer.setTileID(x, y, tileid);
  	}
docs: Set the global ID of a tile at specified location in the map
  
  @param x
  The x location of the tile
  @param y
  The y location of the tile
  @param layerIndex
  The index of the layer to set the new tileid
  @param tileid
  The tileid to be set