The next maxima version will officially introduce the line styles "dashed"
and "dash_dots".
Besides that it will add new line styles. To make them work the "dashed"
terminal option for pngcairo has to be set.
If it isn't these line styles will be drawn as solid lines instead.
Merge pull request #328 from gunterkoenigsmann/NewLineStyles

Support all line styles from the upcoming version of maxima.