redist 4.2.0

• Deprecate functionality that is provided by redistmetrics package.
• Improve contiguity checking speed drastically.
• Support for multiple independent scoring functions in redist_shortburst().
  With multiple scorers, the algorithm will stochastically explore to try to
  find the largest Pareto frontier for the scores. The frontier can be accessed with
  attr(<plans obj>, "pareto_score").
• Removes the MPI vignette which relied on older implementations of redist.mcmc(), which was replaced by redist.flip() a few years ago, and finally redist_flip().