Add new export storage: command
Add a export storage which executes a command with arguments
%f subsituted by filename = each exported image will be executed with cmomand
%F substituted by filenames = execution is done when all images are exported and commandline argument will be all images exported
gimp %f, will export and open each exported image in GIMP
tar -cf mypics.tar.gz %F --gzip, will export a tar archive with all images included..