add check for selectable scatterternary trace:
add check for selectable scatterternary trace:

- only scatterternary traces with mode 'markers' or/and 'text'
  can be selected

iongroup/plotly.js,aburato/plotly.js,plotly/plotly.js,asolagmbh/plotly.js,asolagmbh/plotly.js,iongroup/plotly.js,plotly/plotly.js,asolagmbh/plotly.js,etpinard/plotly.js,aburato/plotly.js,plotly/plotly.js,etpinard/plotly.js,plotly/plotly.js,iongroup/plotly.js,etpinard/plotly.js