The vertical scrollbar state is stored internally within the control,
so should be used when possible.  This will become more necessary when
windowless richedit controls are implemented, and there will no hWnd
to pass to GetScrollInfo.

Comparing the editor as apposed to the handle to the window will work
just as well right now, but will also work when there is no window
handle to make a comparison with, which will be the case with
windowless richedit controls.

The code for the ME_EnsureVisible function does exactly what
EM_SCROLLCARET does, yet this code is duplicated in order to handle
this message.  It is simpler to just use the existing function to
implement the message, and avoid internally sending the EM_SCROLLCARET
when this function is available.

d3dxof: Add a test to dump an X object data (enabled when objects.txt and templates.txt are present).