Index: node_modules/d3-quadtree/src/quadtree.js
===================================================================
--- node_modules/d3-quadtree/src/quadtree.js	(revision e4c61dd6cd86e06265bc2bd91adba84a0f04044a)
+++ node_modules/d3-quadtree/src/quadtree.js	(revision e4c61dd6cd86e06265bc2bd91adba84a0f04044a)
@@ -0,0 +1,73 @@
+import tree_add, {addAll as tree_addAll} from "./add.js";
+import tree_cover from "./cover.js";
+import tree_data from "./data.js";
+import tree_extent from "./extent.js";
+import tree_find from "./find.js";
+import tree_remove, {removeAll as tree_removeAll} from "./remove.js";
+import tree_root from "./root.js";
+import tree_size from "./size.js";
+import tree_visit from "./visit.js";
+import tree_visitAfter from "./visitAfter.js";
+import tree_x, {defaultX} from "./x.js";
+import tree_y, {defaultY} from "./y.js";
+
+export default function quadtree(nodes, x, y) {
+  var tree = new Quadtree(x == null ? defaultX : x, y == null ? defaultY : y, NaN, NaN, NaN, NaN);
+  return nodes == null ? tree : tree.addAll(nodes);
+}
+
+function Quadtree(x, y, x0, y0, x1, y1) {
+  this._x = x;
+  this._y = y;
+  this._x0 = x0;
+  this._y0 = y0;
+  this._x1 = x1;
+  this._y1 = y1;
+  this._root = undefined;
+}
+
+function leaf_copy(leaf) {
+  var copy = {data: leaf.data}, next = copy;
+  while (leaf = leaf.next) next = next.next = {data: leaf.data};
+  return copy;
+}
+
+var treeProto = quadtree.prototype = Quadtree.prototype;
+
+treeProto.copy = function() {
+  var copy = new Quadtree(this._x, this._y, this._x0, this._y0, this._x1, this._y1),
+      node = this._root,
+      nodes,
+      child;
+
+  if (!node) return copy;
+
+  if (!node.length) return copy._root = leaf_copy(node), copy;
+
+  nodes = [{source: node, target: copy._root = new Array(4)}];
+  while (node = nodes.pop()) {
+    for (var i = 0; i < 4; ++i) {
+      if (child = node.source[i]) {
+        if (child.length) nodes.push({source: child, target: node.target[i] = new Array(4)});
+        else node.target[i] = leaf_copy(child);
+      }
+    }
+  }
+
+  return copy;
+};
+
+treeProto.add = tree_add;
+treeProto.addAll = tree_addAll;
+treeProto.cover = tree_cover;
+treeProto.data = tree_data;
+treeProto.extent = tree_extent;
+treeProto.find = tree_find;
+treeProto.remove = tree_remove;
+treeProto.removeAll = tree_removeAll;
+treeProto.root = tree_root;
+treeProto.size = tree_size;
+treeProto.visit = tree_visit;
+treeProto.visitAfter = tree_visitAfter;
+treeProto.x = tree_x;
+treeProto.y = tree_y;