fix(DynamicLineChart): update DynamicLineChart example to work again
fix(DynamicLineChart): update DynamicLineChart example to work again

(1) Remove Events mixin from DynamicLineChart. (2) Use Vega data update API to make dynamic updates.

Kitware/candela,Kitware/candela,Kitware/candela,Kitware/candela,Kitware/candela