bugfix(2596): ft_sourcegrandaverage now properly uses a tmpcfg instead of passing on the master cfg to ft_selectdata. this ensures that cfg.inputfile is no longer broken. 


git-svn-id: svn+ssh://svn.fcdonders.nl/home/svnroot/fieldtrip/trunk@9645 0cf7c7f0-3615-4144-b4e6-68da3bce3cd0