Repaired some broken variables.

knowledge-space.php

@@ -91,9 +91,9 @@ function update_space() {
     if (current_user_can("edit_posts")) {
         $plugin_dir = plugin_dir_path(__FILE__);
         // Use json encoding.
-        $payload = json_encode($_POST["payload"]);
-        $filename = $plugin_dir . $payload["space"] . ".json";
-        $result = file_put_contents($filename, $payload["graph"]);
+        $payload = json_encode($_POST["graph"]);
+        $filename = $plugin_dir . $_POST["space"] . ".json";
+        $result = file_put_contents($filename, $payload);
 
         //echo print_r($_POST);
         echo "Saved file at ";