Two-mode "combine" visualisation with dna_plotNetwork in red, green, and blue

[leifeld]

Two-mode network visualizations using dna_plotNetwork are currently displayed in one single color, even when the combine qualifier aggregation is used, which should display the edges in red (for conflict), green (for congruence), and blue (mixed). Note that integer qualifiers may produce a high number of combinations that cannot be readily mapped into these three colors.

[JBGruber]

See the answer here for working code that we can build on.

[leifeld]

Tagging @TimHenrichsen