sync reference.json at https://github.com/mapnik/reference.json/commit/bbfd176574d2da09d886c6657f9c15c0b9c97ef3
sync reference.json at https://github.com/mapnik/reference.json/commit/bbfd176574d2da09d886c6657f9c15c0b9c97ef3

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