Initial work on #789
Fixed the frame's built-in navigation UI's visibility.
Updated the InterestingPage.xaml and implemented more things in MetroNavigationWindow. Updated the default layout of the MetroNavigationwindow with a Glow and some margins around the frame.
Tweaks to the navigation demo: added a title. Added an opt-in "feature" for applying the clean style to the navigation window.
Updated documentation.
Documentation and event implementation.
Forgot to implement FragmentNavigation. Also fixed the documentation.
Added BackStack, ForwardStack and RemoveJournalEntry.
Added a Forward Button.
Merge pull request #801 from Amrykid/another-metronavigationwindow-attempt

[WIP] Another MetroNavigationWindow Attempt