Convert backend code to ES modules

Bundling code now with Rollup for its flat bundling and tree shaking
support. Front end code still goes through Webpack for browser support.

lib/extensions.js

@@ -18,10 +18,9 @@
  */
 "use strict";
 
-const childProcess = require("child_process");
-const crypto = require("crypto");
-
-const config = require("./config");
+import { fork } from "child_process";
+import crypto from "crypto";
+import * as config from "./config";
 
 const TIMEOUT = config.get("EXT_TIMEOUT");
 
@@ -36,11 +35,11 @@ function messageHandler(message) {
   }
 }
 
-function run(args, callback) {
+export function run(args, callback) {
   const scriptName = args[0];
 
   if (!processes[scriptName]) {
-    const p = childProcess.fork("lib/extension-wrapper", [scriptName]);
+    const p = fork("lib/extension-wrapper", [scriptName]);
     processes[scriptName] = p;
 
     p.on("error", () => {
@@ -91,7 +90,7 @@ function kill(process, callback) {
   }, 100);
 }
 
-function killAll(callback) {
+export function killAll(callback) {
   let counter = 1;
   for (const n in processes) {
     ++counter;
@@ -102,6 +101,3 @@ function killAll(callback) {
   }
   if (--counter === 0 && callback) callback();
 }
-
-exports.run = run;
-exports.killAll = killAll;