Update CHANGELOG.md

Author: gkjohnson

CHANGELOG.md

@@ -5,6 +5,10 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/)
 and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.html).
 
 ## [0.4.20] - Unreleased
+### Added
+- TilesRenderer: Add "queued" status and stats counter for tiles in addition to "downloading" and "parsing".
+- TilesRenderer now removes tiles from the download queue if they are no longer needed for rendering. Tiles will continue to process if they are mid-download or parsing.
+
 ### Changed
 - ImageOverlayPlugin: Textures are now assumed to be straight alpha.
 - ImageOverlayPlugin: Refactor image overlays to afford drawing directly to region textures.