When downloading several files or folders, name the archive 'item1[+n].zip', and ensure that filenames are encoded correctly

package.json

@@ -59,6 +59,7 @@
     ],
     "c9plugins": {
         "c9.ide.language": "#79bcb2fe06",
+        "c9.ide.language.core": "#undefined",
         "c9.ide.language.css": "#be07d72209",
         "c9.ide.language.generic": "#3949510863",
         "c9.ide.language.html": "#22fdc74869",

plugins/c9.ide.download/download.js

@@ -91,24 +91,30 @@ define(function(require, exports, module) {
         }
 
         function downloadProject() {
-            vfs.download("/", info.getWorkspace().name + getArchiveFileExtension());
+            vfs.download("/", makeArchiveFilename(info.getWorkspace().name));
         }
 
         function downloadPaths(paths) {
-            vfs.download(paths, info.getWorkspace().name + getArchiveFileExtension());
+            var lastPart = paths[0].match(/([^\/]*)\/?$/)[1];
+            var filename = lastPart ? (lastPart + "[+" + (paths.length - 1) + "]") : info.getWorkspace().name;
+            vfs.download(paths, makeArchiveFilename(filename));
         }
 
         function downloadFolder(path) {
             var withTrailingSlash = path.replace(/\/*$/, "/");
             var parts = withTrailingSlash.split("/");
-            var lastPart = parts[parts.length - 2];
-            vfs.download(withTrailingSlash, lastPart + getArchiveFileExtension());
+            var folderName = parts[parts.length - 2];
+            vfs.download(withTrailingSlash, makeArchiveFilename(folderName));
         }
 
         function downloadFile(path) {
             vfs.download(path.replace(/\/*$/, ""), null, true);
         }
 
+        function makeArchiveFilename(filename) {
+            return filename + getArchiveFileExtension();
+        }
+
         function getArchiveFileExtension() {
             var downloadFilesAs = settings.get(SETTING_PATH);
             if (downloadFilesAs === 'auto' || !downloadFilesAs) {

plugins/c9.vfs.client/vfs_client.js

@@ -193,12 +193,12 @@ define(function(require, exports, module) {
                 extraPaths = path;
                 path = path[0];
                 extraPaths = "," + extraPaths.map(function(p) {
-                    return p[0] == path[0] && p != path ? escape(p) : "";
+                    return p[0] == path[0] && p != path ? encodeURI(p) : "";
                 }).filter(Boolean).join(",");
             }
             window.open(vfsUrl(path) + extraPaths
                 + "?download" 
-                + (filename ? "=" + escape(filename) : "")
+                + (filename ? "=" + encodeURIComponent(filename) : "")
                 + (isfile ? "&isfile=1" : ""));
         }