redline "eating up" table cell divider when exported to .doc - tentative fix submitted to gerrit

I have submitted a fix (https://gerrit.libreoffice.org/#/c/15340/) that
requires someone knowledgeable with redline and .doc exporting to review.

The marker used in Word to identify table cell division was being
included in the track-changes deletion from the following cell if
the deletion was the first node in the cell.  This would cause the
two table cells to merge into one when changes were accepted by
Word.  (Problem not seen in LibreOffice itself, only in Word.)

I don't understand this code - I just figured out something that fixed
my problem and tried to make it as targeted as possible. I'm not really
sure of the implications - it just didn't seem to do anything bad to my
sample document.... The biggest problem is that this is called at the
end of EVERY cell, regardless of whether it is touching a redline. I
couldn't figure out how to recognize when that occurs. So the
possibility of introducing a regression is fairly high...  Several
testcases are attached to the bug report.  It is super easy to reproduce
the problem.  Simply open the testcase in LibreOffice and save.  Then in
MSWord, accept all of the tracked changes.

Thanks,
Justin