Fix for the FlatSlider changes made by @HansHuang
Merge pull request #1034 from Amrykid/fix-flatsider-35c75ed6600881ef3bd121c11f371c4057797c78

Fix for the FlatSlider changes made by @HansHuang
Add NumericUpDownChangedRoutedEventArgs in order to achieve the request in #1032

#Closes #1032
Changed to correct RoutedEvent
Added missing File
Oops, missed it in .net40
Merge pull request #1036 from xxMUROxx/hotfix/NumericUpDown

Add NumericUpDownChangedRoutedEventArgs...