/download_zip_action
create a .zip file containing layout changes only

Sourcecode in Layout/actions.js:
1:   function download_zip_action() {
2:      try {
3:         var data = this.evalDownload(false);
4:         res.contentType = "application/zip";
5:         res.writeBinary(data);
6:      } catch (err) {
7:         res.message = new Exception("layoutDownload");
8:         res.redirect(this.href());
9:      }
10:     return;
11:  }