Creates a rater, that requires, that every pair of lines in a group have a distance of at least a given constant value. The function firstly requires an integer attribute, in order to determine the distance between 2 lines, by calculating the integer difference of the line values given the attribute. The second argument is an integer literal, that states the minimal required difference, in order to avoid any cost. The cost of an incoming group is the additional distance required, in order to avoid any cost.