go_back_to_original_process
takes the infered parameters with a BM
on a rescaled tree, and gives back the equivalent parameters of the OU on
the original process.
go_back_to_original_process(phy_original, known.selection.strength,
sBM_variance, params)
the original phylogenetic tree
the known selection strength of the original OU.
boolean. Is the root random ?
the infered parameters of the BM on the re-scaled tree.
params_scOU the equivalent parameters of the OU on the original tree.