Update CHANGELOG.md

Author: gkjohnson

CHANGELOG.md

@@ -20,6 +20,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 - ImageOverlayPlugin: Refactor image overlays to afford drawing directly to region textures.
 - GeoJSONOverlay: Add "redraw" function to redraw the geojson once it's changed
 - Renamed the "cached" tile subfield to "engineData".
+- Moved a number of tile fields into "traversal" and "internal" subfields on "tile" object.
 
 ### Fixed
 - Fix mouse offset in Controls.