Added explicate setup instructions.
narrow_guage -> narrow_gauge
Merge remote-tracking branch 'nvkelso/patch-1'
Remove duplicate geometries in favor of using attachments
Show rail sooner
high_road(numeric, box3d) function

Allows one to replace all planet_osm_line_z* layers with one containing SQL similar to:

(SELECT * FROM high_road(!scale_denominator!, !bbox!)) AS high_road

...which will then query the appropriate table for a given zoom level.
Carto version of the default stylesheet

Uses high_road() to simplify and separate layers by kind.  Without layer
separation, ::outline and ::casing attachments were getting stomped on by
additional features (e.g. minor roads covering parts of a highway's casing).

Layer separation also makes it easier to selectively turn off roads by type.
Buildings, water bodies, and land
Proper casting
Group by feature not zoom
Paths at 17+
Merge remote-tracking branch 'origin/carto'