metR 0.9.1

New Features

• as.discretised_scale() is a quick way of created a discretised version of any
  continuous scale.

• stroke.colour is now an accepted aesthetic for geom_text_contour().

Bugfixes

• The computations in MixingRatio() were wrong. Now they are fixed.

• I really wanted geom_arrow() to automatically add the arrow legend, but the
  workarounds I managed to write were brittle and couldn't handle even slight
  changes in people's code (see #130). The definitive
  answer is that this is simply not possible due to limitations on how ggplot2 works
  (see tidyverse/ggplot2#4291).
  This release, then, backtracks those workarounds and tries to accept the things I cannot change.