General usability improvements

* Reevaluate all featuers stroke widths for shadow, casing, stroke
* Shadow width is important to make sure all features are easily clickable
* Casing width is important to see oneway arrows
* Make sure all line styles have normal and low-zoom variants
* Show directional arrows for all waterway types

modules/osm/tags.js

@@ -35,6 +35,9 @@ export var osmOneWayTags = {
         'yes': true
     },
     'waterway': {
+        'canal': true,
+        'ditch': true,
+        'drain': true,
         'river': true,
         'stream': true
     }