Allow map rotation

[camelloar]

Sometimes in the selected zone (especially in cities) the alignment of streets are not vertical & horizontal (N-S and W-E), and could be in diagonal, or have a shape that dindn´t fit well in portrait or landscape, getting a lot more of elements than desired or a less zoom factor to get all into shape.
I (and some OSM fellows in our telegram´s group) request you (if posible) to allow rotate the selection or the output (not NORTH UP).
I tried to rotate in inkscape, and get a awful work; getting the names rotated, between another things that went wrong (and no think in put a grid or a street list).
Regards.

[hholzgra]

I'd love to be able to correctly rotate directly at rendering time, too, but unfortunately the Mapnik renderer does not support this yet.

My own motivation was to be able to create neighborhood map oriented in the direction of view, instead of north up, as you often see them on tourist information columns, like those used in London:

http://3.bp.blogspot.com/-ItBjBjJIrs8/UXKneZvx-qI/AAAAAAAAANk/sDkDnDM9-HU/s1600/2013-04-15+12.42.56.jpg

There is a long standing Mapnik feature request for this, and there even was an experimental patch for this at some point, but unfortunately that patch got lost when the Mapnik source repository and bug tracker were moved to Github. I tried to contact the original author of the patch, but never got a response :(

mapnik/mapnik#531

[hholzgra]

See also newer mapnik request mapnik/mapnik#4374