Comment on how import statements work

src/import.js

@@ -1,6 +1,8 @@
 /* @license
 
   Copyright (c) 2011 Lauri Paimen <lauri@paimen.info>
+  Copyright (c) 2015 Pavel Vasev <pavel.vasev@gmail.com> - initial
+                     and working import implementation.
 
   Redistribution and use in source and binary forms, with or without
   modification, are permitted provided that the following conditions
@@ -68,6 +70,7 @@ function parseQML(file) {
 /**
  * Get URL contents. EXPORTED.
  * @param url {String} Url to fetch.
+ * @param skipErrorLogging {boolean} if true, the failed fetch is not error (used with conjuction of importPathList).
  * @private
  * @return {mixed} String of contents or false in errors.
  */
@@ -86,7 +89,7 @@ getUrlContents = function (url,skipErrorLogging) {
        // because without exception, "" then goes to parser, and it failes with strange errors. 
        if (!skipErrorLogging) 
          throw e;
-       return "";
+       return false;
     }
     return xhr.responseText;
 }
@@ -97,8 +100,24 @@ getUrlContents = function (url,skipErrorLogging) {
  * @return {Object} Object, where .internals lists qmldir internal references
  *                          and .externals lists qmldir external references.
  */
+
+/*  Note on how importing works.
+
+   * parseQML gives us `tree.$imports` variable, which contains information from `import` statements.
+
+   * After each call to parseQML, we call engine.loadImports(tree.$imports).
+     It in turn invokes readQmlDir() calls for each import, with respect to current component base path and engine.importPathList().
+
+   * We keep all component names from all qmldir files in global variable `engine.qmldir`.
+   
+   * In construct() function, we use `engine.qmldir` for component url lookup.
+
+   Reference import info: http://doc.qt.io/qt-5/qtqml-syntax-imports.html 
+   Also please look at notes and TODO's in qtcore.js::loadImports() and qtcore.js::construct() methods.
+*/
+
 readQmlDir = function (url) {
-    var qmldir = getUrlContents(url + "/qmldir"), // Modifies url here!
+    var qmldir = getUrlContents(url + "/qmldir", true), // loading url contents with skipping errors
         lines,
         line,
         internals = {},