SlintPlot 0.4.3

Fixed

• FunnelChart: on Linux, Windows and in browsers, where Slint draws with
  femtovg, every stage was drawn a pixel larger all round, so the gap
  between stages was about half of gap, with a stray line at its ends.
  The stages are now drawn counterclockwise and back to their start, as the
  other charts' shapes since 0.4.2, and a test checks that Slint takes them
  as solid.