Accessor and mutator created for full stop centered flag, removed
bit field.

See commit description in 8bfccd3a ("vcl: Create accessor
and mutator for font scaling in FontMetric") for reasoning behind
patch.

Unit tests
- check to ensure that can set full stop centered flag
- check equality operator on FontMetric after setting full stop
  centered flag

Change-Id: I9cacb0fbf9ea65cfebcaebdc9f0481c0a796cbcf
Reviewed-on: https://gerrit.libreoffice.org/21413Reviewed-by: Chris Sherlock <chris.sherlock79@gmail.com>
Tested-by: Chris Sherlock <chris.sherlock79@gmail.com>