* make it possible to set the colors of the graphs from outside
* more tests
* Needs patch(es) to GD::Graph:
  - graphs with angled text at the bottom (like 45° since the email addresses or
    filter rules are pretty long)
  - the linear and yearly prediction numbers overlap, this should be handled
    better by GD::Graph (like placing the lower _below_ the line instead of
    _over_ it and thus inside the upper number)
* When the archive is newer than the index, re-create the index automatically.
* SA scatter and daily_score graphs.