Bug 145

If we take two columns of a dataset, place it into a command. It is probably good to link to each input an extra column that is automatically added to the output column. A good example is a large place with many columns but only one coilumn with images. If we want to execute a gray operation on all the images, then we want to use the same image code but we still want to preserver the original images. A good solution is probably to make sure that each command has some form of id.