Reduce maximum memory used for vertex sorting (#170)

* Add logging for out-of-memory debugging

* Use less memory for sub-sorting

* Reduce maximum memory used for vertex sorting

CHANGELOG.md

@@ -1,3 +1,7 @@
+# 2.37.1
+
+* Reduce maximum memory used for vertex sorting
+
 # 2.37.0
 
 * Speed up tile-join overzooming and make it use less memory, by not including empty child tiles in the enumeration