mapbox: handle map move on 'moveend' only
mapbox: handle map move on 'moveend' only

- no need map mapbox opts to layout.mapbox and
  fire events at each step during the move,
  handling this at the end works just fine for our needs.

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