mizer 2.3.1

• Resolved conflict in mizerPredRate() between the argument t and the
  function base::t().
• Assert that upgradeParams() must be called with a MizerParams object and
  upgradeSim() with a MizerSim object.
• Errors changed to warnings in getRequiredRDD()
• renameSpecies() no longer fails when linecolour and linetype are of
  different lengths.
• matchYields() now also works for a model with only a single species.
• setInitialValues() can now average over a time_range.
• getSSB(), getBiomass(), getN(), getYieldGear() and getYield()
  can now be called with a MizerParams object as well as with a MizerSim
  object. (#200)
• Updated the shiny app in inst/shiny/selectivity_effects to current mizer
  version.