* plotting of directed lines: slight offset correction

  Subtract 0.5 from the delta, so there are no (occasional) gaps
  between directed lines in different directions.

  Alternatively I could *add* 0.5 to always force gaps; maybe this
  could be an option.
* data change: replaced all categories with multi-? to single-?
* bbbike: removed color support for "??" category

  This category does not exist anymore, last occurrences in bbbike
  data were removed.
* fragezeichen-outdoor.bbd: added a new color for +1w
* data update