bugfix-fixed bug when format is empty. see bug2432

git-svn-id: svn+ssh://svn.fcdonders.nl/home/svnroot/fieldtrip/trunk@9101 0cf7c7f0-3615-4144-b4e6-68da3bce3cd0
automatically synchronized identical files to revision 9101

git-svn-id: svn+ssh://svn.fcdonders.nl/home/svnroot/fieldtrip/trunk@9102 0cf7c7f0-3615-4144-b4e6-68da3bce3cd0