Fix temporary error when imports are used, support circular imports

Fixes #59

Fixes #159 -
this is a particularly notable instance of the bug, since `TypeError:
DosDatetime is not a constructor` is an error that initially everyone
gets when they open the Web IDE in a fresh browser (this is because
`zip.ksy` is selected by default, and it is affected by the bug since it
contains an import).

See kaitai-io/kaitai_struct#1074 and
kaitai-io/kaitai_struct_compiler#264 - the
actual fix was done in the KSC-generated JS code, which was changed to
allow interdependent format modules to be loaded (and added to the
global context in the case of the Web IDE) in any order. However, this
was a backwards-incompatible change, so this set of Web IDE changes just
updates our code to work with the new compiler.

src/v1/kaitaiWorker.ts

@@ -51,7 +51,16 @@ function exportValue(obj: any, debug: IDebugInfo, path: string[], noLazy?: boole
         if (debug && debug.enumName) {
             result.enumName = debug.enumName;
             var enumObj = myself;
-            debug.enumName.split(".").forEach(p => enumObj = enumObj[p]);
+            var enumPath = debug.enumName.split(".");
+
+            // Because of https://github.com/kaitai-io/kaitai_struct/issues/1074,
+            // KSC-generated modules export a plain object (not the constructor
+            // function directly) - for example, the exported value from the
+            // `Zip.js` module is `{ Zip: function (_io, _parent, _root) {...} }`.
+            //
+            // This means we have to use the top-level name twice in the path resolution.
+            enumPath.unshift(enumPath[0]);
+            enumPath.forEach(p => enumObj = enumObj[p]);
 
             var flagCheck = 0, flagSuccess = true;
             var flagStr = Object.keys(enumObj).filter(x => isNaN(<any>x)).filter(x => {
@@ -114,7 +123,7 @@ importScripts("../../lib/_npm/kaitai-struct/KaitaiStream.js");
 var apiMethods = {
     initCode: (sourceCode: string, mainClassName: string, ksyTypes: IKsyTypes) => {
         wi.ksyTypes = ksyTypes;
-        eval(`${sourceCode}\nwi.MainClass = ${mainClassName};`);
+        eval(`${sourceCode}\nwi.MainClass = ${mainClassName}.${mainClassName};`);
     },
     setInput: (inputBuffer: ArrayBuffer) => wi.inputBuffer = inputBuffer,
     reparse: (eagerMode: boolean) => {
@@ -156,4 +165,4 @@ myself.onmessage = (ev: MessageEvent) => {
 
     //console.log("[Worker] Send response", msg, ev);
     myself.postMessage(msg);
-};
+};