use bare "three" imports

Previously we were importing from specific three/src files. Why change? Because:
    - we can still tree shake
    - we were actually (indeirectly) using bare imports before, too. E.g., ThreeStrap imports from "three/examples/jsm/controls/OrbitControls", and OrbitControls imports bare "three"
    - "three" seems like the more official import pattern; it's what is documented at https://threejs.org/docs/#manual/en/introduction/Installation

See also unconed/mathbox#49

src/binder.js

@@ -1,4 +1,4 @@
-import { EventDispatcher } from "three/src/core/EventDispatcher.js";
+import { EventDispatcher } from "three";
 
 export class Binder {
   static bind(context, globals) {

src/controls/VRControls.js

@@ -10,7 +10,7 @@
  * for more info.
  */
 
-import { Matrix4 } from "three/src/math/Matrix4.js";
+import { Matrix4 } from "three";
 
 export class VRControls {
   constructor(object, onError) {

src/core/camera.js

@@ -1,6 +1,4 @@
-import { Camera } from "three/src/cameras/Camera.js";
-import { OrthographicCamera } from "three/src/cameras/OrthographicCamera.js";
-import { PerspectiveCamera } from "three/src/cameras/PerspectiveCamera.js";
+import { Camera, OrthographicCamera, PerspectiveCamera } from "three";
 import { Bootstrap } from "../bootstrap";
 
 Bootstrap.registerPlugin("camera", {

src/core/renderer.js

@@ -1,4 +1,4 @@
-import { WebGL1Renderer } from "three/src/renderers/WebGL1Renderer.js";
+import { WebGL1Renderer } from "three";
 import { Bootstrap } from "../bootstrap";
 
 Bootstrap.registerPlugin("renderer", {

src/core/scene.js

@@ -1,4 +1,4 @@
-import { Scene } from "three/src/scenes/Scene.js";
+import { Scene } from "three";
 import { Bootstrap } from "../bootstrap";
 
 Bootstrap.registerPlugin("scene", {

src/extra/controls.js

@@ -1,4 +1,4 @@
-import { PerspectiveCamera } from "three/src/cameras/PerspectiveCamera.js";
+import { PerspectiveCamera } from "three";
 import { Bootstrap } from "../bootstrap";
 
 Bootstrap.registerPlugin("controls", {

src/renderers/VRRenderer.js

@@ -4,8 +4,7 @@
  * @author wwwtyro https://github.com/wwwtyro
  * @author unconed https://github.com/unconed
  */
-import { PerspectiveCamera } from "three/src/cameras/PerspectiveCamera.js";
-import { Vector3 } from "three/src/math/Vector3.js";
+import { PerspectiveCamera, Vector3 } from "three";
 
 export class VRRenderer {
   constructor(renderer, hmd) {

test/core/camera.spec.js

@@ -1,6 +1,5 @@
 import * as Threestrap from "../../src";
-import { OrthographicCamera } from "three/src/cameras/OrthographicCamera.js";
-import { PerspectiveCamera } from "three/src/cameras/PerspectiveCamera.js";
+import { OrthographicCamera, PerspectiveCamera } from "three";
 
 describe("camera", function () {
   it("installs a perspective camera", function () {

test/core/render.spec.js

@@ -1,7 +1,5 @@
 import * as Threestrap from "../../src";
-import { Scene } from "three";
-import { PerspectiveCamera } from "three/src/cameras/PerspectiveCamera.js";
-
+import { Scene, PerspectiveCamera } from "three";
 
 describe("render", function () {
   it("renders the scene on update", function () {

test/core/renderer.spec.js

@@ -1,5 +1,5 @@
 import * as Threestrap from "../../src";
-import { WebGL1Renderer } from "three/src/renderers/WebGL1Renderer.js";
+import { WebGL1Renderer } from "three";
 
 describe("renderer", function () {
   it("installs the canvas into the body", function () {

test/core/scene.spec.js

@@ -1,5 +1,5 @@
 import * as Threestrap from "../../src";
-import { Scene } from "three/src/scenes/Scene.js";
+import { Scene } from "three";
 
 describe("scene", function () {
   it("makes a scene", function () {

test/extra/controls.spec.js

@@ -1,5 +1,5 @@
 import * as Threestrap from "../../src"
-import { PerspectiveCamera } from "three/src/cameras/PerspectiveCamera.js";
+import { PerspectiveCamera } from "three";
 import { OrbitControls } from "three/examples/jsm/controls/OrbitControls";
 
 

webpack.config.ts

@@ -38,10 +38,6 @@ const library: Configuration = {
   },
   externals: {
     three: "THREE",
-    "three/src/core/EventDispatcher.js": "THREE",
-    "three/src/renderers/WebGL1Renderer.js": "THREE",
-    "three/src/scenes/Scene.js": "THREE",
-    "three/src/cameras/PerspectiveCamera.js": "THREE",
   },
   optimization: {
     minimize: true,