Added missing file Flyout.php

I saw this file was missing and was throwing an error in the admin. So i downloaded it from server and created a pull request for you.

Application Error: File not found

Exception_PathFinder, code: 0

Additional information:

file: View/Flyout.php
type: php
attempted_locations:
0: /Users/Qambar/Work/elexu.com/admin/lib/View/Flyout.php
1: /Users/Qambar/Work/elexu.com/lib/View/Flyout.php
2: /Users/Qambar/Work/elexu.com/shared/lib/View/Flyout.php
3: /Users/Qambar/Work/atk4/lib/View/Flyout.php
class: View_Flyout
namespace:
orig_class: View_Flyout
/Users/Qambar/Work/atk4/lib/PathFinder.php:219