updated raster colorizer support
Convert minzoom/maxzoom parameters on Layer properties.
add raster colorizer (https://github.com/mapnik/mapnik/wiki/RasterColorizer) support to master - closes #5 - refs mapbox/tilemill#761 - depends on https://github.com/mapnik/mapnik/commit/41772edbd7be0d8b2aca774bb9f2f17b1e9d7cd1
Fix fadeout
Allow layers to be rendered without datasources.
Merge branch 'layerzoom'
point to master mapnik-reference
output both path to json mismatches to make debugging test failures easier
fix expected result so test passes because it appears #239 is not actually a regression
fix failing tests in master
Add a man page for carto