window: Make the navigation buttons linked and separate the home button

Also, remove the 12px at the end of the navigation buttons.

https://bugzilla.gnome.org/show_bug.cgi?id=735398
window: Use the new support for RTL icons in GtkIconTheme

https://bugzilla.gnome.org/show_bug.cgi?id=735399
Remove the close action from the gear menu

https://bugzilla.gnome.org/show_bug.cgi?id=735400
Fixed typo