tangrams/tangram — pull request #59 by meetar (2014-11-08 01:42:41+00:00)
Title: modify a_layer by sort_key for overlapping road outlines

Following the example of modifying all the outlines' a_layer by -0.25 – If I understand this mechanism correctly, we might need to normalize all of the sort_keys to fit within 0..1, so we don't accidentally push any of the roads into another layer's a_layer.