* CreateParams.cs: Add a couple of helper methods and do a less string

* CreateParams.cs: Add a couple of helper methods and do a less string
  concatenation in ToString.
* XplatUIX11.cs: Add an TranslateClientRectangleToXClientRectangle
  overload that takes a Control parameter, since this method may be
  called before a control is assigned to the hwnd (from
  CreateWindow), and update CreateWindow to use the new overload. In
  GetMenuOrigin subtract the title bar from the y position if the
  form has a window manager (since we're painting it and not X).
* XplatUIWin32.cs: If we can get a form in GetMenuOrigin use the form's
  CreateParams to calculate the origin (since border sizes may vary).
  In ScreenToMenu only subtract the title height if we actually have
  a title.
* MdiWindowManager.cs: Override MenuHeight to always return 0, since
  mdi children never have menus of themselves.
* InternalWindowManager.cs: Implement menu handling like form does.
  Added GetMenuOrigin to calculate the menu origin, can't use the
  CreateParams from the form like normally since it's lying.
* Hwnd.cs: Implement GetBorderSize better (in the sense more
  windows-like) and add Inflate and comparison operators to the
  Borders type. When calculating MenuOrigin and it's a form with a
  window manager, use the window manager to calculate it.

svn path=/trunk/mcs/; revision=75867