Allow features that would be dropped dynamically to become multiplier features (#199)

* Postpone tagging features as being the first of a multiplier cluster

* Upgrade some dynamically dropped features to multiplier features

* Still don't let it put more features in a cluster than is allowed

* Update tests

* Make the current multiplier cluster size per-layer

* Make sure the first non-empty-geometry in the layer is marked as primary

* Improve comments

* Update changelog and version

* Remove commented out debugging printf

* Factor out duplicated code

CHANGELOG.md

@@ -1,3 +1,7 @@
+# 2.45.0
+
+* Adjust tile size limit with --retain-points-multiplier dynamically within each tile, to allow multiplier features at high zooms if other features are being dropped as-needed
+
 # 2.44.0
 
 * Add --unidecode-data option to allow case-insensitive filter comparisons of transliterated strings