These functions were just being used for addition, so it was simpler to
remove the functions and modify the places it was used.

The ME_StrRelPos2 and ME_PosToVPos were just simple wrappers around
ME_StrRelPos, and ME_PosToVPos wasn't being used.

These two functions were being used for simple operations, to get the
first or last character when pre-computing flags for splitting runs.

The call to ME_GetCharBack wasn't even giving the correct result, it
would always return -1 since it is being called with nPos of 0.

This patch simplifies the code by removing the functions and getting the
characters directly from the string.

These functions were probably previously needed because of some wierd
special handling of backspace characters, but currently there is no
reason why the nLen field can't be accessed directly.

Having to functions that just access the string length field just causes
slightly more effort for someone to look at the code, because they need
to enter the function to find out what it actually is doing.

The function was just returning the second parameter.  It had some
commented out code that indicated that previously backslashes weren't
included in the length.  Native wordpad doesn't handle backspaces in a
special way, so this must have been an internal representation that
complicated finding the position of characters.

ME_GetCursorCoordinates had two conditions that were always taken.  The
first condition was if(pCursor->pRun->type == diRun) was following an
assertion making the exact same check.  The next one, if(row), should
always be taken, otherwise the richedit controls are in a corrupt state,
therefore an assertion is more appropriate.

I found that ME_MakeStringB was previously unused, and that the other
ME_MakeString functions repeated code that was already in ME_MakeStringB.
Making ME_MakeStringB static and using it to avoid duplicate code seemed
like a better idea than removing the function.

Previously it found the start or end by traversing the linked lists of
run, rows, paragraphs, and cells from the current position of the
cursors.  Clearly it is better to get the start or end directly to make
it a constant time operation.

Wrapping is needed to be done even when repainting isn't done since
later messages expect line breaks to reflect the current text.  Some
message can specify not to paint the sceen, but this should prevent
wrapping from being done.

cryptui: Ensure a certificate's private key is exportable before allowing it to be selected for export.

cryptui: Skip password page when moving backward through the export wizard if it wasn't shown in the first place.

- A HWND can be safely marshaled over a LONG as its payload is not
  a pointer but a user handle.
- Use GetWindowLongPtr instead of GetWindowLong to retrieve a pointer.

Relaxing the tests on older versions of Windows caused a couple tests
to fail on more recent ones, which was unintended.