JS: enable circular imports by exporting object (not function)

[generalmimon]

Resolves kaitai-io/kaitai_struct#1074

This change breaks backward compatibility with 0.10 and older, but allows for circular imports (in all JavaScript module systems) and out-of-order module loading in a "browser globals" context (the latter is particularly relevant in the Web IDE, as explained at kaitai-io/kaitai_struct#1074). In short, it does this by switching from the UMD envelope returnExports.js to modified commonjsStrict.js.

The BC break is that until now the generated modules exported the constructor function directly, whereas now they export the object containing the constructor function under the only object key that matches the format module name. The same behavior is expected from imported opaque types and custom processors as well.

[generalmimon]

Here's how this compiler change affects the JavaScript code generated from imports0.ksy:

--- 1/compiled-old/javascript/Imports0.js
+++ 2/compiled/javascript/Imports0.js
@@ -3,11 +3,11 @@
 (function (root, factory) {
   if (typeof define === 'function' && define.amd) {
-    define(['kaitai-struct/KaitaiStream', './HelloWorld'], factory);
-  } else if (typeof module === 'object' && module.exports) {
-    module.exports = factory(require('kaitai-struct/KaitaiStream'), require('./HelloWorld'));
+    define(['exports', 'kaitai-struct/KaitaiStream', './HelloWorld'], factory);
+  } else if (typeof exports === 'object' && exports !== null && typeof exports.nodeType !== 'number') {
+    factory(exports, require('kaitai-struct/KaitaiStream'), require('./HelloWorld'));
   } else {
-    root.Imports0 = factory(root.KaitaiStream, root.HelloWorld);
+    factory(root.Imports0 || (root.Imports0 = {}), root.KaitaiStream, root.HelloWorld || (root.HelloWorld = {}));
   }
-}(typeof self !== 'undefined' ? self : this, function (KaitaiStream, HelloWorld) {
+})(typeof self !== 'undefined' ? self : this, function (Imports0_, KaitaiStream, HelloWorld_) {
 var Imports0 = (function() {
   function Imports0(_io, _parent, _root) {
@@ -20,5 +20,5 @@ var Imports0 = (function() {
   Imports0.prototype._read = function() {
     this.two = this._io.readU1();
-    this.hw = new HelloWorld(this._io, this, null);
+    this.hw = new HelloWorld_.HelloWorld(this._io, this, null);
   }
   Object.defineProperty(Imports0.prototype, 'hwOne', {
@@ -33,4 +33,4 @@ var Imports0 = (function() {
   return Imports0;
 })();
-return Imports0;
-}));
+Imports0_.Imports0 = Imports0;
+});