Show ferry routes [Closes #251]

[mapmeld]

Style based on how ferry routes are implemented in standard Mapnik: https://github.com/openstreetmap/mapnik-stylesheets/blob/master/inc/layer-ferry-routes.xml.inc

Screenshot from my environment (I don't have DEM data so it's a little off)

[yohanboniface]

Thanks a lot @mapmeld for this! :)

I'm not sure though myself that ferry routes are in the scope of the "Humanitarian and development" focused rendering, but I'm not even sure it's not ;)
@skorasaurus @jaakkoh @severinmenard thoughts?

[mapmeld]

I noticed they were missing because I was recently mapping / hiking near Lascahobas, Haiti. We took a small ferry across the river to a very isolated village (zoom out from this area on OSM: http://www.openstreetmap.org/#map=16/18.8502/-71.9415 ). There are likely other, longer routes which are not yet on OSM, but people were relying on the ferry to travel to Lascahobas and do business there.

Also there are a few countries in the world made entirely of small islands; ferries are important to show there.

[yohanboniface]

Those sounds like good arguments :)

[yohanboniface]

If route=ferry is a subset of #ferry, so we should add the filter on the main selector (#ferry[route='ferry']) otherwise we can have non ferry routes displayed with default style. Other option, that may the best, is to filter out in the SQL itself so we only have the routes we are interested in.

[mapmeld]

@yohanboniface now that you mention it, I do have it filtered out in the SQL! I can simplify this quite a bit, then

[jaakkoh]

I agree that ferries / other alike are an important mode of transportation in many low-income countries and with that IMO certainly within the scope of economic development agenda. As/when they are an integral part of the transport system they fall into the need to sufficient base mapping that feed into disaster preparedness too. So, great if these could be integrated.
Thanks again and in advance!

[skorasaurus]

@mapmeld Good work :) I agree that they deserve to be included.

[yohanboniface]

Thanks :)