refactor setting scenario colours

[fbenke-pik]

When setting scenario colours, rather choose from a predefined set of colours than relying on mip::plotstyle(), because

• plotstyle introduces unforeseeable side effects (see plotstyle.add() modifies renv cache on the cluster, with bad consequences mip#114)
• we do not maintain colours for our scenarios in plotstlye anyways, so we always get the default colours (which will now be defined explicitly im piamPlotComparison)

[0UmfHxcvx5J7JoaOhFSs5mncnisTJJ6q]

Umm.
Would that affect all the plots? Or just the file reference table? Because I do not much care about the background colours in the table …

[fbenke-pik]

The reference table colours are the same ones used for line plots

[fbenke-pik]

Or maybe not? This might not fix the problem after all, if showLinepPlots also retrieves the colours using plotstyle().
Will check ...

[0UmfHxcvx5J7JoaOhFSs5mncnisTJJ6q]

They all use plotstyle().

[fbenke-pik]

Closed, as it does not fix the problem as expected.