metR 0.9.0 - Cirrus fibratus

New Features

• I'm very happy with discretised_scale(), which is a type of scale which takes a
  discrete values that are the result of some discretisation and treats them as
  continuous. It's, in a sense, the inverse of the new ggplot2::binned_scale().
  Whereas. ggplot2::binned_scale() takes continuous values and then discretises
  them, discretised_scale() takes discrete values which where the result of some
  discretisation procedure (such as the levels of geom_contour_fill()/ggplot2::geom_contour_filled())
  and allows you to treat them as continuous.

• Related to that, geom_contour_fill() now gains a new computed aesthetic called level_d,
  which is the same as level but forces ggplot2 to automatically use the new discretised scale.

• AnchorBreaks() gains a bins argument to mimic the default functionality of
  MakeBreaks().

• New label_placement_minmax() to label contours at the maximum and minimum
  points of a contour (mimicking isoband's behaviour)

• geom_contour_tanaka() now has a (rather experimental) argument smooth which allows to smooth
  the transition between segments.

Bugfixes

• Fixes error introduced in previous version when geom_arrow() had mappings other
  than dx and dy. (Thanks Santiago!)

• The level derived aesthetic from geom_contour_fill() now returns and ordered factor
  with the correct labels that can be interpreted by ggplot2::guide_colorsteps(). This might
  a breaking change!

• geom_label_contour() lives! The previous release rewrote much of the way geom_text_contour()
  worked, but I messed up and didn't realised that the new code had broken geom_label_contour()
  (to be honest, I'd almost totally forgotten about it :P). (fixes #126, thanks @kongdd)