Release 4.0-beta8

This release has a number of changes under the hood, but not very many user-visible changes.

• Changes:
  • Write out tree with branch-lengths scaled according to weighted average of partition scales.
  • Print the alignment length including fixed-alignment partitions.
• Phylogenetics
  • Update likelihoods and other infrastructure to handle multifurcating trees and data on internal nodes.
• Tools
  • Add benchmarking script benchmark.py