Streamline single/multipage API

[RussKie]

Closes #13

Proposed changes

• reduce the public API surface to only static entry points:

  public static TaskDialogButton ShowDialog(TaskDialogPage page);
  public static TaskDialogButton ShowDialog(IntPtr hwndOwner, TaskDialogPage page);
  public static TaskDialogButton ShowDialog(IWin32Window owner, TaskDialogPage page);

• remove now defunct events and their plumbing
• to facilitate the navigation to another page add TaskDialogPage.Navigate(TaskDialogPage page), that will allow to write something like:

  button1.Click += (s, e) => button1.BoundPage.Navigate(page2);

[kpreisser]

Thanks!

[kpreisser]

This will always be false as it will result in comparing a non-null IntPtr? (e.g. IntPtr.Zero) with a null IntPtr?.

[RussKie]

Aye, it was a mindless copy-paste...

[RussKie]

If you think I've missed anything, by all means feel free to correct it