Move to new modular layer structure

layers/road/road.yaml

@@ -0,0 +1,12 @@
+layer:
+  id: "road"
+  description: Roads
+  buffer_size: 4
+  srs: +proj=merc +a=6378137 +b=6378137 +lat_ts=0.0 +lon_0=0.0 +x_0=0.0 +y_0=0.0 +k=1.0 +units=m +nadgrids=@null +wktext +no_defs +over
+  fields:
+    class: String
+  datasource:
+    srid: 900913
+    query: (SELECT * FROM layer_road(!bbox!, z(!scale_denominator!))) AS t
+schema:
+  - ./road.sql