[Rivet] plotting of multi-weight curves in 3.0.0alpha1

[Frank Siegert]

Hi Chris,

> I guess it would already help a lot if we could specify line properties in
> the plot file for certain curves/variations only, e.g. something like
>
> # BEGIN PLOT /BLAH/*[MUR0.5_MUF1_PDF261000]
> LineColor=blue
> LineStyle=dashed
> # END PLOT

Isn't something like that already possible like in the second part of
this config file example:
http://rivet.hepforge.org/make-plots.html#_configuration_files
?

Cheers,
Frank