Line & contour plots for parameter sweep visualization

The bubble plots used for parameter sweeps in some cases less informative than more traditional line (attached deco2012a.PNG) & contour plots (attached nf3.png) used to present parameter sweep information in typical research papers.

The bubbles shall be kept, and an option added to choose the traditional representation.

Question: which shall be the default? When someone sends a screenshot on the mailing list I will inevitably ask to see the "traditional" visualization, so that would be my preference. However, this means updating tutorial materials, etc.