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_name/water_name.yaml

@@ -14,9 +14,11 @@ layer:
     name_de: German name `name:de` if available, otherwise `name` or `name:en`.
     class:
       description: |
-          Distinguish between `lake`, `ocean` and `sea`.
+          Distinguish between `lake`, `ocean`, `bay`, `strait`, and `sea`.
       values:
       - lake
+      - bay
+      - strait
       - sea
       - ocean
     intermittent: