gfse: edit abstract syntax in text mode with instant syntax error reporting

This is an experimental feature. It requires server support for parsing and is
thus not available while offline, unlike most other editing functionality.

src/www/gfse/cloud2.js

@@ -193,6 +193,12 @@ function gfshell(cmd,cont) {
     })
 }
 
+// Check the syntax of a source module
+function check_module(path,source,cont) {
+    var enc=encodeURIComponent;
+    http_get_json("/parse?"+enc(path)+"="+enc(source),cont)
+}
+
 // Check the syntax of an expression
 function check_exp(s,cont) {
     function check(gf_message) {