CppunitTest_sw_ooxmlexport: clean up testfdo79817

Instead of checking the third paragraph, remove everything else from the
bugdoc, so checking the only paragraph is enough.

Change-Id: I74e8db16cb1f27370ac88d9dff136aaeceb63cdb
DOCX import: handle SDT around citation field

There were two problems here:

1) Citation field was around a run, but was exported as around the
paragraph.

2) The SDT properties were discarded, as they were inserted into a
character context that was thrown away. To fix this, add a (character
properties) context to the field state, so when it's inserted, it can
have the requested properties.

Change-Id: Ic36deff616060f049147874633c6c7264ae8ecf2
sw/qa/extras/README: document how to run a single test

This was already documented in the code, but first it got copy&pasted
several times, then now it's "hidden" in a header, so not so easy to
find.

Change-Id: I6c6814a14bb6208d9f31ee66f0c0f9b843ee7157