Index: node_modules/d3-drag/src/constant.js
===================================================================
--- node_modules/d3-drag/src/constant.js	(revision e4c61dd6cd86e06265bc2bd91adba84a0f04044a)
+++ node_modules/d3-drag/src/constant.js	(revision e4c61dd6cd86e06265bc2bd91adba84a0f04044a)
@@ -0,0 +1,1 @@
+export default x => () => x;
Index: node_modules/d3-drag/src/drag.js
===================================================================
--- node_modules/d3-drag/src/drag.js	(revision e4c61dd6cd86e06265bc2bd91adba84a0f04044a)
+++ node_modules/d3-drag/src/drag.js	(revision e4c61dd6cd86e06265bc2bd91adba84a0f04044a)
@@ -0,0 +1,194 @@
+import {dispatch} from "d3-dispatch";
+import {select, pointer} from "d3-selection";
+import nodrag, {yesdrag} from "./nodrag.js";
+import noevent, {nonpassive, nonpassivecapture, nopropagation} from "./noevent.js";
+import constant from "./constant.js";
+import DragEvent from "./event.js";
+
+// Ignore right-click, since that should open the context menu.
+function defaultFilter(event) {
+  return !event.ctrlKey && !event.button;
+}
+
+function defaultContainer() {
+  return this.parentNode;
+}
+
+function defaultSubject(event, d) {
+  return d == null ? {x: event.x, y: event.y} : d;
+}
+
+function defaultTouchable() {
+  return navigator.maxTouchPoints || ("ontouchstart" in this);
+}
+
+export default function() {
+  var filter = defaultFilter,
+      container = defaultContainer,
+      subject = defaultSubject,
+      touchable = defaultTouchable,
+      gestures = {},
+      listeners = dispatch("start", "drag", "end"),
+      active = 0,
+      mousedownx,
+      mousedowny,
+      mousemoving,
+      touchending,
+      clickDistance2 = 0;
+
+  function drag(selection) {
+    selection
+        .on("mousedown.drag", mousedowned)
+      .filter(touchable)
+        .on("touchstart.drag", touchstarted)
+        .on("touchmove.drag", touchmoved, nonpassive)
+        .on("touchend.drag touchcancel.drag", touchended)
+        .style("touch-action", "none")
+        .style("-webkit-tap-highlight-color", "rgba(0,0,0,0)");
+  }
+
+  function mousedowned(event, d) {
+    if (touchending || !filter.call(this, event, d)) return;
+    var gesture = beforestart(this, container.call(this, event, d), event, d, "mouse");
+    if (!gesture) return;
+    select(event.view)
+      .on("mousemove.drag", mousemoved, nonpassivecapture)
+      .on("mouseup.drag", mouseupped, nonpassivecapture);
+    nodrag(event.view);
+    nopropagation(event);
+    mousemoving = false;
+    mousedownx = event.clientX;
+    mousedowny = event.clientY;
+    gesture("start", event);
+  }
+
+  function mousemoved(event) {
+    noevent(event);
+    if (!mousemoving) {
+      var dx = event.clientX - mousedownx, dy = event.clientY - mousedowny;
+      mousemoving = dx * dx + dy * dy > clickDistance2;
+    }
+    gestures.mouse("drag", event);
+  }
+
+  function mouseupped(event) {
+    select(event.view).on("mousemove.drag mouseup.drag", null);
+    yesdrag(event.view, mousemoving);
+    noevent(event);
+    gestures.mouse("end", event);
+  }
+
+  function touchstarted(event, d) {
+    if (!filter.call(this, event, d)) return;
+    var touches = event.changedTouches,
+        c = container.call(this, event, d),
+        n = touches.length, i, gesture;
+
+    for (i = 0; i < n; ++i) {
+      if (gesture = beforestart(this, c, event, d, touches[i].identifier, touches[i])) {
+        nopropagation(event);
+        gesture("start", event, touches[i]);
+      }
+    }
+  }
+
+  function touchmoved(event) {
+    var touches = event.changedTouches,
+        n = touches.length, i, gesture;
+
+    for (i = 0; i < n; ++i) {
+      if (gesture = gestures[touches[i].identifier]) {
+        noevent(event);
+        gesture("drag", event, touches[i]);
+      }
+    }
+  }
+
+  function touchended(event) {
+    var touches = event.changedTouches,
+        n = touches.length, i, gesture;
+
+    if (touchending) clearTimeout(touchending);
+    touchending = setTimeout(function() { touchending = null; }, 500); // Ghost clicks are delayed!
+    for (i = 0; i < n; ++i) {
+      if (gesture = gestures[touches[i].identifier]) {
+        nopropagation(event);
+        gesture("end", event, touches[i]);
+      }
+    }
+  }
+
+  function beforestart(that, container, event, d, identifier, touch) {
+    var dispatch = listeners.copy(),
+        p = pointer(touch || event, container), dx, dy,
+        s;
+
+    if ((s = subject.call(that, new DragEvent("beforestart", {
+        sourceEvent: event,
+        target: drag,
+        identifier,
+        active,
+        x: p[0],
+        y: p[1],
+        dx: 0,
+        dy: 0,
+        dispatch
+      }), d)) == null) return;
+
+    dx = s.x - p[0] || 0;
+    dy = s.y - p[1] || 0;
+
+    return function gesture(type, event, touch) {
+      var p0 = p, n;
+      switch (type) {
+        case "start": gestures[identifier] = gesture, n = active++; break;
+        case "end": delete gestures[identifier], --active; // falls through
+        case "drag": p = pointer(touch || event, container), n = active; break;
+      }
+      dispatch.call(
+        type,
+        that,
+        new DragEvent(type, {
+          sourceEvent: event,
+          subject: s,
+          target: drag,
+          identifier,
+          active: n,
+          x: p[0] + dx,
+          y: p[1] + dy,
+          dx: p[0] - p0[0],
+          dy: p[1] - p0[1],
+          dispatch
+        }),
+        d
+      );
+    };
+  }
+
+  drag.filter = function(_) {
+    return arguments.length ? (filter = typeof _ === "function" ? _ : constant(!!_), drag) : filter;
+  };
+
+  drag.container = function(_) {
+    return arguments.length ? (container = typeof _ === "function" ? _ : constant(_), drag) : container;
+  };
+
+  drag.subject = function(_) {
+    return arguments.length ? (subject = typeof _ === "function" ? _ : constant(_), drag) : subject;
+  };
+
+  drag.touchable = function(_) {
+    return arguments.length ? (touchable = typeof _ === "function" ? _ : constant(!!_), drag) : touchable;
+  };
+
+  drag.on = function() {
+    var value = listeners.on.apply(listeners, arguments);
+    return value === listeners ? drag : value;
+  };
+
+  drag.clickDistance = function(_) {
+    return arguments.length ? (clickDistance2 = (_ = +_) * _, drag) : Math.sqrt(clickDistance2);
+  };
+
+  return drag;
+}
Index: node_modules/d3-drag/src/event.js
===================================================================
--- node_modules/d3-drag/src/event.js	(revision e4c61dd6cd86e06265bc2bd91adba84a0f04044a)
+++ node_modules/d3-drag/src/event.js	(revision e4c61dd6cd86e06265bc2bd91adba84a0f04044a)
@@ -0,0 +1,28 @@
+export default function DragEvent(type, {
+  sourceEvent,
+  subject,
+  target,
+  identifier,
+  active,
+  x, y, dx, dy,
+  dispatch
+}) {
+  Object.defineProperties(this, {
+    type: {value: type, enumerable: true, configurable: true},
+    sourceEvent: {value: sourceEvent, enumerable: true, configurable: true},
+    subject: {value: subject, enumerable: true, configurable: true},
+    target: {value: target, enumerable: true, configurable: true},
+    identifier: {value: identifier, enumerable: true, configurable: true},
+    active: {value: active, enumerable: true, configurable: true},
+    x: {value: x, enumerable: true, configurable: true},
+    y: {value: y, enumerable: true, configurable: true},
+    dx: {value: dx, enumerable: true, configurable: true},
+    dy: {value: dy, enumerable: true, configurable: true},
+    _: {value: dispatch}
+  });
+}
+
+DragEvent.prototype.on = function() {
+  var value = this._.on.apply(this._, arguments);
+  return value === this._ ? this : value;
+};
Index: node_modules/d3-drag/src/index.js
===================================================================
--- node_modules/d3-drag/src/index.js	(revision e4c61dd6cd86e06265bc2bd91adba84a0f04044a)
+++ node_modules/d3-drag/src/index.js	(revision e4c61dd6cd86e06265bc2bd91adba84a0f04044a)
@@ -0,0 +1,2 @@
+export {default as drag} from "./drag.js";
+export {default as dragDisable, yesdrag as dragEnable} from "./nodrag.js";
Index: node_modules/d3-drag/src/nodrag.js
===================================================================
--- node_modules/d3-drag/src/nodrag.js	(revision e4c61dd6cd86e06265bc2bd91adba84a0f04044a)
+++ node_modules/d3-drag/src/nodrag.js	(revision e4c61dd6cd86e06265bc2bd91adba84a0f04044a)
@@ -0,0 +1,28 @@
+import {select} from "d3-selection";
+import noevent, {nonpassivecapture} from "./noevent.js";
+
+export default function(view) {
+  var root = view.document.documentElement,
+      selection = select(view).on("dragstart.drag", noevent, nonpassivecapture);
+  if ("onselectstart" in root) {
+    selection.on("selectstart.drag", noevent, nonpassivecapture);
+  } else {
+    root.__noselect = root.style.MozUserSelect;
+    root.style.MozUserSelect = "none";
+  }
+}
+
+export function yesdrag(view, noclick) {
+  var root = view.document.documentElement,
+      selection = select(view).on("dragstart.drag", null);
+  if (noclick) {
+    selection.on("click.drag", noevent, nonpassivecapture);
+    setTimeout(function() { selection.on("click.drag", null); }, 0);
+  }
+  if ("onselectstart" in root) {
+    selection.on("selectstart.drag", null);
+  } else {
+    root.style.MozUserSelect = root.__noselect;
+    delete root.__noselect;
+  }
+}
Index: node_modules/d3-drag/src/noevent.js
===================================================================
--- node_modules/d3-drag/src/noevent.js	(revision e4c61dd6cd86e06265bc2bd91adba84a0f04044a)
+++ node_modules/d3-drag/src/noevent.js	(revision e4c61dd6cd86e06265bc2bd91adba84a0f04044a)
@@ -0,0 +1,13 @@
+// These are typically used in conjunction with noevent to ensure that we can
+// preventDefault on the event.
+export const nonpassive = {passive: false};
+export const nonpassivecapture = {capture: true, passive: false};
+
+export function nopropagation(event) {
+  event.stopImmediatePropagation();
+}
+
+export default function(event) {
+  event.preventDefault();
+  event.stopImmediatePropagation();
+}