informative colouring of sequence id

Sequence ID colours are transferred to trees and PCA plots, and very useful to visually indicate the distribution of a particular attribute amongst the sequences in the alignment.

Currently, they are assigned either via the annotation file or randomly via the tree partition. It would also be useful to :
Colour sequence ID by a specific feature or annotation:
 * colourschemes associated with
   - non-positional features (score, label, density of non-pos annotation)
   - sequence associated annotation rows