Unittest generation of text for chapter entries in the TOC

Conflicts:
	sw/inc/ToxTextGenerator.hxx
	sw/qa/cppunit/tox/test_ToxTextGenerator.cxx
	sw/source/core/tox/ToxTextGenerator.cxx

Change-Id: I343958f85fb6718215a0caa456a825d72f168a57
Reviewed-on: https://gerrit.libreoffice.org/9612
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>