fix crash loading ooo#93570-3.doc
fix crash loading ooo#93570-3.doc

regression from f2945255df273404ee2457dcf761cb8f334b732b
cp#2013101510000026: doc import of comments affecting more text nodes

use Move(fnMoveBackward, fnGoNode) to at least ensure we stop going
backwards when we run out of valid places to go backwards to.

This still isn't great because the distance between two msword character
indexes only equates to the same distance between our characters in the very
simple cases

Change-Id: I248fd12c067577d2f1fd64f48583321eb6d453e4

JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core