scattergeo: add proper calc step
scattergeo: add proper calc step

- which skips and cast lon/lat values
- fixes https://github.com/plotly/plotly.js/issues/963
- note that 'locations[i]' -> feature must still be
  done at the plot (after the topojson is loaded)

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