Add place=quarter to city subdivisions (#1065)

This adds `place=quarter` which was introduced in 2011 as a subdivision
of villages/towns/cities as a value that sits between `place=suburb` and
`place=neighbourhood`. It has by now been used over 40,000 times and is
rendered in the OSM-Carto.

layers/place/mapping.yaml

@@ -174,5 +174,6 @@ tables:
       - village
       - hamlet
       - suburb
+      - quarter
       - neighbourhood
       - isolated_dwelling