Fix URL bug in #821, and fix #864

gui.js

@@ -83,9 +83,15 @@ var SoundIconMorph;
 var JukeboxMorph;
 
 // Get the full url without "snap.html"
-var baseUrl = document.URL.split('/');
-baseUrl.pop(baseUrl.length - 1);
-baseUrl = baseUrl.join('/') + '/';
+var baseURL = (function getPath(location) {
+    var origin, path, slash;
+    path = location.pathname; // starts with a /
+    origin = location.origin; // has no trailing /
+    slash = path.lastIndexOf('/');
+    path = path.slice(0, slash); // keep a trailing /
+    return origin + path;
+}(window.location));
+
 
 // IDE_Morph ///////////////////////////////////////////////////////////
 
@@ -2497,10 +2503,10 @@ IDE_Morph.prototype.projectMenu = function () {
         function () {
             // read a list of libraries from an external file,
             var libMenu = new MenuMorph(this, 'Import library'),
-                libUrl = baseUrl + 'libraries/' + 'LIBRARIES';
+                libUrl = baseURL + 'libraries/' + 'LIBRARIES';
 
             function loadLib(name) {
-                var url = baseUrl + 'libraries/' + name + '.xml';
+                var url = baseURL + 'libraries/' + name + '.xml';
                 myself.droppedText(myself.getURL(url), name);
             }
 
@@ -4219,7 +4225,7 @@ IDE_Morph.prototype.getURLsbeOrRelative = function (url) {
     var request = new XMLHttpRequest(),
         myself = this;
     try {
-        request.open('GET', baseUrl + url, false);
+        request.open('GET', baseURL + url, false);
         request.send();
         if (request.status === 200) {
             return request.responseText;
@@ -4660,7 +4666,7 @@ ProjectDialogMorph.prototype.setSource = function (source) {
                 myself.nameField.setContents(item.name || '');
             }
             src = myself.ide.getURL(
-                baseUrl + 'Examples/' + item.name + '.xml'
+                baseURL + 'Examples/' + item.name + '.xml'
             );
 
             xml = myself.ide.serializer.parse(src);
@@ -4714,9 +4720,9 @@ ProjectDialogMorph.prototype.getLocalProjectList = function () {
 ProjectDialogMorph.prototype.getExamplesProjectList = function () {
     var dir,
         projects = [];
-        //alert(baseUrl);
+        //alert(baseURL);
 
-    dir = this.ide.getURL(baseUrl + 'Examples/');
+    dir = this.ide.getURL(baseURL + 'Examples/');
     dir.split('\n').forEach(
         function (line) {
             var startIdx = line.search(new RegExp('href=".*xml"')),
@@ -4835,7 +4841,7 @@ ProjectDialogMorph.prototype.openProject = function () {
     if (this.source === 'cloud') {
         this.openCloudProject(proj);
     } else if (this.source === 'examples') {
-        src = this.ide.getURL(baseUrl + 'Examples/' + proj.name + '.xml');
+        src = this.ide.getURL(baseURL + 'Examples/' + proj.name + '.xml');
         this.ide.openProjectString(src);
         this.destroy();
     } else { // 'local'