Re-adding index.js for easier imports

package.json

@@ -3,6 +3,7 @@
   "version": "1.2.0",
   "description": "Core functions, classes and components for RecogitoJS",
   "sideEffects": false,
+  "main": "src/index.js",
   "scripts": {
     "test": "NODE_ENV=test ./node_modules/.bin/mocha --require @babel/register"
   },

src/index.js

@@ -0,0 +1,8 @@
+export { default as Editor } from './editor/Editor';
+export { default as I18n } from './i18n';
+export { default as WebAnnotation } from './WebAnnotation';
+export { default as Selection } from './Selection';
+export { default as createEnvironment } from './Environment';
+
+export * from './Icons';
+export * from './utils';