bugfix - and one more, see previous two comments


git-svn-id: svn+ssh://svn.fcdonders.nl/home/svnroot/fieldtrip/trunk@8297 0cf7c7f0-3615-4144-b4e6-68da3bce3cd0
enhancement - improve check on presence of avg and trial, both are fine as long as consistent with each other

git-svn-id: svn+ssh://svn.fcdonders.nl/home/svnroot/fieldtrip/trunk@8298 0cf7c7f0-3615-4144-b4e6-68da3bce3cd0