gfse: initial support for module extension

There is a new way to create a new grammar based on an existing grammar:
by extending it. (It is also possible to clone an existing grammar, a before.)

src/www/gfse/cloud2.js

@@ -36,7 +36,7 @@ function upload(g) {
 	    var cname=g.basename+g.concretes[i].langcode+".gf";
 	    //files.push(cname);
 	    form.appendChild(hidden(cname,
-				    show_concrete(g.basename)(g.concretes[i])));
+				    show_concrete(g)(g.concretes[i])));
 	}
 	editor.appendChild(form);
 	form.submit();