eulerr 5.0.0

New features

• error_plot() is a new function that offers diagnostic plots of
  fits from euler(), letting the user visualize the error in the
  resulting Euler diagram.

Major changes

• euler() once again uses the residual sums of squares, rather than the
  stress metric, as optimization objective, which means that
  output is always scaled appropriately to input (#28).
• plot.euler() now uses the
  polylabelr package to position
  labels for the overlaps of the ellipses, which has improved
  performance in plotting complicated diagrams considerably and reduced
  the amount of code in this package greatly.
• The c++ internals have been rewritten using more memory-efficient, performant
  and expressive code.

Minor changes

• The euler.data.frame() method (and by proxy the euler.matrix() method)
  can now take matrices with factors in addition to the previously supported
  logical and integer (binary) input. The function will dummy code the variables
  for the user.
• A few performance fixes.
• Additional unit tests.
• Previously deprecated arguments to plot.euler() have been made defunct.
• Added a data set, plants, to exemplify the list method for euler().
• Added a data set, fruits, to exemplify the data.frame method for euler().
• euler.data.frame() gains an argument sep, which is a character vector
  used to separate dummy-coded factors if there are factors or characters in the
  input.
• Added a data set, organisms, to exemplify the matrix method for euler().
• Added a data set, pain, to exemplify the table method for euler().
• euler.table() gains an argument, factor_names, for specifying
  whether the factor names should be included when generating dummy-coded
  variables in case the input is a data.frame with character or factor vectors
  or if the input is a table with more than two columns or rows.
• Parts of the eulerr under the hood vignette has been branched off into
  a new vignette regarding visualization.

Bug fixes

• Empty combinations can now be provided and will be plotted (generating
  completely blank plots).
• euler.list() now passes its ellipsis argument along properly. (#33,
  thanks, @banfai)
• Several spelling and grammar mistakes were corrected in vignettes and
  documentation.