Package wgs84tiler
provides slicing functions for slippy map (tiled map) generation
It output out/Z/X/Y.png files , where Z is the zoom level, and X and Y identify the tile.
go get -u github.com/konogan/wgs84tiler
http://godoc.org/github.com/konogan/wgs84tiler
need to rewrite