Show number of messages for undo

app/src/main/java/eu/faircode/email/FragmentMessages.java

@@ -4676,7 +4676,7 @@ public class FragmentMessages extends FragmentBase implements SharedPreferences.
                 // Show undo snackbar
                 final Snackbar snackbar = Snackbar.make(
                         content,
-                        getString(R.string.title_moving, getDisplay(result)),
+                        getString(R.string.title_move_undo, getDisplay(result), result.size()),
                         Snackbar.LENGTH_INDEFINITE);
                 snackbar.setAction(R.string.title_undo, new View.OnClickListener() {
                     @Override

app/src/main/res/values/strings.xml

@@ -777,7 +777,7 @@
     <string name="title_reply_list">Reply to list</string>
     <string name="title_reply_receipt">Send read receipt</string>
     <string name="title_reply_template">Reply with template</string>
-    <string name="title_moving">Moving to %1$s</string>
+    <string name="title_move_undo">Moving to %1$s (%2$d)</string>
     <string name="title_open_with">Open with</string>
     <string name="title_authentication_failed">%1$s authentication failed</string>