Cost colors
While randomizing the colors during the work on #51 (closed) it became apparent that it would be quite useful to have configurable fixed colors either by cost category (#40 (closed)) or by each cost individually.
As always also uncategorized costs exist, the latter needs to be implemented anyway. As https://github.com/timrdf/vsr/wiki/Linked-Open-Colors is dead, its probably best to use http://dbpedia.org/ontology/Colour for describing it on data level.
See also https://stackoverflow.com/questions/12325736/publicly-available-rdf-color-ontology