cp#1000018 RTF import: empty para at the end of footnote text got lost

Updated 3 testcases, in all cases first checked that the new behavior
matches what Word does.

Also added a new test, to check that empty para at footnote end is now
kept.

(cherry picked from commit 9389cf78e304a5a99bcf1745b9388e14ac36281a)

Conflicts:
	sw/qa/extras/rtfimport/rtfimport.cxx
	writerfilter/source/rtftok/rtfdocumentimpl.cxx

Change-Id: I96b8788feb4d730b5a64ba3a743311a0180ab41f
cp#1000018 RTF export: avoid additional paragraph at footnote end

(cherry picked from commit 8299924b750f74f799dc683134788a285b38bd72)

Conflicts:
	sw/source/filter/ww8/rtfattributeoutput.cxx

Change-Id: I430a7d705208f197050a7d521c9c20b267c33f26