legendry 0.3.0: Articuno

This minor version is a small feature release, introducing several new guides,
arguments and changes to keys.

• New guide guide_legend_manual() for user defined keys (#88)
• New guide guide_axis_plot() to place side-plots (#43)
• New guide guide_axis_upset() to place symbols in upset matrices next to axes.
  Also comes with key_upset() to match (#38).
• New guide guide_axis_symbols() for a more manual version of placing symbols.
  Also comes with key_symbols() to match (#38).
• New guide guide_axis_annotation() to jot down annotations. Includes the
  helpers annotate_top/right/bottom/left() for convenience (#89).
• New key key_range_rle() to create a range annotation based on run-length
  encoding.
• New arguments guide_axis_base(subtitle) and guide_axis_nested(subtitle)
  make it easier to title custom axes (#102)
• New arguments guide_legend_cross(row_title, col_title, subtitle_position)
  to display subtitles over dimensions (#79).
• compose_stack(side.titles) also work in non-position guides (#101)
• Changed the margins and inferred justification of the legendry.axis.subtitle
  and legendry.legend.subtitle theme elements.
• Changed ... argument in many key_*() functions to transfer graphical
  properties like colour or linewidth to guides. Different parts of guides
  can be targeted by specifying
  text_colour/line_colour/rect_colour/point_colour.
• Changed key_group_split() to preserve order of labels better, rather than
  re-sorting them (#100).
• Updated title mechanism to comply with ggplot2#6200 (#104)
• Updated lifecycle of new_compose(), compose_ontop(), compose_stack()
  from 'experimental' to 'stable'.
• Fixed a bug where empty titles in legends contributed to spacing. Visual
  tests depending on legendry may see subtle positioning shifts (#113).
• Fixed a bug where guide_legend_group() struggled to merge different
  scales (#112).