plotIndv colors and pch by default in sPLS-DA

[Kim-Anh Le Cao]

When running a sPLS-DA, we should put Y as an output, and reuse that output in plotIndiv to color the samples with respect to their class, per default.

Note: -This should also be done for plotd3Indiv (warning, the pch is different in that case) -We should use the color.mixo (10 colors max, if more than 10, then we can use color.jet)

Florian is going to implement this in meta.pls. We would need to change that in plsda/splsda

[Florian Rohart]

Just to confirm, this will be implemented in V6