This change also introduces the following changes:

1) Special initialization routine just for the unit test runs.  In
   particular, SfxMedium instance needs to be set even for a brand-new
   document (as in the actual run-time), or else the document would be
   always labeled "read-only".  This prevented us from testing various
   code in Calc, which this commit fixes.

2) Several cppunit checks that checked for incorrect results, which
   passed because we happened to be getting those incorrect results
   due to the issue with the SfxMedium instance not being set.

3) Unfortunately now the test for cell function MATCH fails for some
   mysterious reason.  The test is disabled temporarily until we figure
   this out.

Change-Id: If231fd99e0ffddcd74f65c7cb5476e7a25f0ac7d