use new mapnik-reference@6.0.0
use new mapnik-reference@6.0.0

pnorman/carto,clhenrick/carto,CartoDB/carto,stefanklug/carto,mapbox/carto,gravitystorm/carto,midnightcomm/carto,CartoDB/carto,tomhughes/carto,madeinqc/carto,1ec5/carto