Merge remote-tracking branch 'upstream/pull/4381'

Author: tomhughes

…p/assets/images/key/mapnik/mainroad7.png …p/assets/images/key/mapnik/mainroad8.pngapp/assets/images/key/mapnik/mainroad7.png renamed to app/assets/images/key/mapnik/mainroad8.png app/assets/images/key/mapnik/mainroad7.png renamed to app/assets/images/key/mapnik/mainroad8.png

@@ -1,8 +1,7 @@
 mapnik:
-  - { min_zoom: 0, max_zoom: 19, name: motorway, image: motorway.png }
-  - { min_zoom: 0, max_zoom: 6, name: main_road, image: mainroad.png }
-  - { min_zoom: 7, max_zoom: 8, name: main_road, image: mainroad7.png }
-  - { min_zoom: 9, max_zoom: 11, name: main_road, image: mainroad9.png }
+  - { min_zoom: 6, max_zoom: 19, name: motorway, image: motorway.png }
+  - { min_zoom: 6, max_zoom: 7, name: main_road, image: mainroad.png }
+  - { min_zoom: 8, max_zoom: 11, name: main_road, image: mainroad8.png }
   - { min_zoom: 12, max_zoom: 19, name: main_road, image: mainroad12.png }
   - { min_zoom: 13, max_zoom: 19, name: track, image: track.png }
   - { min_zoom: 13, max_zoom: 19, name: bridleway, image: bridleway.png }