change place node expansion for large area table

So far we've used a buffer around a place node to define its
potential address reach. This had two problems: the buffer was
so large that addresses often contain false positives and the
buffer is really distorted when getting closer to the poles.

Change the buffer here to draw a bounndig box at a certain
distance in meter. This means that we always use the same
box everywhere on the planet and can make the extent much
smaller. Using a box has the advantage that it is much faster
to figure out if a point is within the box.

settings/address-levels.json

@@ -2,6 +2,8 @@
 { "tags" : {
       "place" : {
           "sea" : [2, 0],
+          "island" : [17, 0],
+          "islet" : [20, 0],
           "continent" : [2, 0],
           "country" : [4, 0],
           "state" : [8, 0],
@@ -10,25 +12,23 @@
           "county" : 12,
           "municipality" : [17, 14],
           "city" : 16,
-          "island" : [17, 0],
           "town" : [18, 16],
+          "borough" : 18,
           "village" : [19, 16],
           "district" : [19, 16],
-          "borough" : [19, 18],
+          "suburb" : [19, 20],
           "hamlet" : 20,
-          "suburb" : 20,
           "croft" : 20,
           "subdivision" : 20,
-          "isolated_dwelling" : 20,
           "allotments" : 20,
-          "farm" : [20, 0],
-          "locality" : [20, 0],
-          "islet" : [20, 0],
-          "mountain_pass" : [20, 0],
-          "neighbourhood" : 22,
-          "quarter" : 22,
+          "neighbourhood" : [20, 22],
+          "quarter" : [20, 22],
+          "isolated_dwelling" : [22, 20],
           "city_block" : 22,
-          "houses" : [28, 0]
+          "mountain_pass" : [20, 0],
+          "houses" : [28, 0],
+          "farm" : [20, 0],
+          "locality" : [20, 0]
       },
       "boundary" : {
           "administrative2" : 4,