Move "clapper_src" dir to "src"

The "clapper_src" directory name was unusual. This was done to make it work as a widget for other apps. Now that this functionality got removed it can be named simply "src" as recommended by guidelines.

src/menu.js

@@ -0,0 +1,13 @@
+const { GObject, Gst, Gtk } = imports.gi;
+const Dialogs = imports.src.dialogs;
+
+var actions = {
+    openLocal: (window) => new Dialogs.FileChooser(window),
+    openUri: (window) => new Dialogs.UriDialog(window),
+    prefs: (window) => new Dialogs.PrefsDialog(window),
+    about: (window) => new Dialogs.AboutDialog(window),
+};
+
+var accels = [
+    ['app.quit', ['q']],
+];