Revamp water label display logic (#1457)

* At zooms 9-13, water labels will now be rendered for water features that are at least 0.25 tiles in size.  This means that water features that are the same size as a 128x128 pixel square will get a point label.
* Labels for large water features are now shown at the lowest zoom at which it's appropriate to show a label.
* Bay and strait names (`natural=bay` and `natural=strait`) are included. 
* Large seas modeled as areas (e.g. Caspian Sea) render as `class=sea` rather than `class=lake`

layers/water/mapping.yaml

@@ -66,6 +66,9 @@ tables:
       type: string
     - name: tags
       type: hstore_tags
+    - name: place
+      key: place
+      type: string
     - name: natural
       key: natural
       type: string