A list of rwty.cumulative objects, one per chain in the input list of chains.
Each rwty.cumulative object contains the cumulative mean split frequencies of clades at sp
windows, and a translation table that converts clade groupings to factors.
Arguments
chains
A list of rwty.chain objects.
burnin
The number of trees to eliminate as burnin. Defaults to zero.
window.size
The number of trees to include in each window (note, specified as a number of sampled trees, not a number of generations)