Wpf Example Change TabControl to ItemsSource

Changed TabControl to use ItemsSource
View -> ViewModel mapping is now handled by DataTemplate
Imported TabControlEx control to prevent tabs from being reloaded each time they've viewed
Added close button to each tab
Added some basic styling to TabItems
Remove duplicate DelegateCommand
Move DelegateCommandT to CefSharp.Wpf project
Expose internals for CefSharp.Wpf to Example project
Add ViewSource command directly to WebView and IWpfWebBrowser
Change MainViewModel to inherit from ViewModelBase - more changes tocome on this
Add ChangeAndNotify method directly into ViewModelBase
Added ctrl->t key cord to open new browser tab