[FEATURE]: Spikelines in scatterternary plots

Hi,

Description

It would be great if we could add spikelines to scatterternary plots, mapping to the a,b,c axes in an analogous way to the spikelines in a scatter plot.

Why should this feature be added?

Adding this feature would help the students we support become proficient in reading data off this plot type.

{
  "ternary": {
    "aaxis": {
      "showspikes": true,
      "spikecolor": "",
      "spikedash": "",
      "spikemode": "",
      "spikesnap": "",
      "spikesthickness": ""
    },
    "baxis": {
      "showspikes": true,
      "spikecolor": "",
      "spikedash": "",
      "spikemode": "",
      "spikesnap": "",
      "spikesthickness": ""
    },
    "caxis": {
      "showspikes": true,
      "spikecolor": "",
      "spikedash": "",
      "spikemode": "",
      "spikesnap": "",
      "spikesthickness": ""
    }
  }
}

Many thanks!

Commencez par comparer le comportement existant des spikelines des scatter plots avec la gestion des axes a, b et c pour les scatterternary plots. Le travail est considéré comme terminé lorsque les scatterternary plots prennent en charge les paramètres de spike demandés et affichent des spikelines analogues à celles des scatter plots.