Report the nw.js version during startup.

pd/nw/index.js

@@ -743,6 +743,8 @@ function post_startup_messages() {
     // These will be the first messages printed to the main Pd window.
     // Later let's use a link to the docs for new users.
     pdgui.post("Welcome to Purr Data");
+    // Report the nw.js version that we're using.
+    pdgui.post("nw.js version " + process.versions["nw"]);
     // Warn the user if the font sizes aren't optimal. Font sizes which
     // aren't optimal result in extra space at the end of object/message
     // boxes