cp#1000017 DOCX/RTF import: avoid fake tab char in footnotes

Word wants this, so it's added by the exporter to the document, but on
import we should ignore it.

(cherry picked from commit b38629ae210b204a6d24d6e9c5c62eaaf563d494)

Conflicts:
	writerfilter/source/dmapper/DomainMapper.cxx
	writerfilter/source/dmapper/DomainMapper_Impl.cxx
	writerfilter/source/dmapper/DomainMapper_Impl.hxx

Change-Id: Idcb669ba624bf462a50a85eb4aacf397afb6efe6