enhancement - make behavior more robust in the presence of nans, or in case pos2dim fails

git-svn-id: svn+ssh://svn.fcdonders.nl/home/svnroot/fieldtrip/trunk@9066 0cf7c7f0-3615-4144-b4e6-68da3bce3cd0
automatically synchronized identical files to revision 9066

git-svn-id: svn+ssh://svn.fcdonders.nl/home/svnroot/fieldtrip/trunk@9067 0cf7c7f0-3615-4144-b4e6-68da3bce3cd0