add support for 3D/4D postgis geometries

[just]

See thread on Mapnik users mailing list.

The PostGIS plugin/WKB reader assumes that geometries are in 2D. Though not standard OGC, PostGIS supports 3D/4D. There are two ways to fix this in Mapnik :

1. Add support for 3D/4D Geometries in wkb reader

2. Use force_2D inside postgis plug-in

[artem]

The third way is to use 'force_2D' in SQL :

(select name, type, force_2D(the_geom) from roads) as roads_2d;