Select new message when notification is clicked

When a new mail notification is clicked, Evolution's current behavior is simply to open the folder with the new mail, without selecting the new message. (Actually, it's even worse: Evolution opens the first folder to have received new mail since the last time a notification was closed, which may or may not be the same folder as the most recent new mail.) This patch makes Evolution select the folder and message displayed in the current notification when that notification is clicked, which is more intuitive behavior.