MVTAnnotationsPlugin: Limit loaded tiles in screen only (#1629)

* Limit loaded tiles in screen only

* Cleanup

* Update the plugin

* Add a basic hierarchy for traversal

* Hierarchy updates

* Updates

* Add unload guards

* Update

* Updates

* Clean up

* Fix event listener

* Fixes

* Fix condition

Author: gkjohnson

example/three/annotationsExample.js

@@ -101,7 +101,6 @@ const KIND_TO_ICON = {
 
 const params = {
 
-	errorTarget: 20,
 	occupancyGrid: false,
 
 };
@@ -309,8 +308,6 @@ function animate() {
 	controls.update();
 
 	// tiles update
-	tiles.errorTarget = params.errorTarget;
-
 	tiles.setResolutionFromRenderer( camera, renderer );
 	tiles.setCamera( camera );
 	camera.updateMatrixWorld();