Implement geom_GeomDensity2dFill

Contours of 2D density estimates would be very helpful in my Shiny application I'm developing which soon should be published.
We would like to use plotly.

Brief description of the problem:

Warning in geom2trace.default(dots[[1L]][[60L]], dots[[2L]][[1L]], dots[[3L]][[1L]]) :
  geom_GeomDensity2dFilled() has yet to be implemented in plotly.
  If you'd like to see this geom implemented,
  Please open an issue with your example code at
  https://github.com/ropensci/plotly/issues

Create plot with geom_density_2d_filled and this has not yet been implemented.

p <- ggplot(df, aes(Y_cm, X_cm)) + geom_density_2d_filled(contour_var="ndensity") 

Comece com o exemplo de R fornecido usando geom_density_2d_filled(contour_var="ndensity") e rastreie o aviso a partir de geom2trace.default. Compare o comportamento solicitado de densidade preenchida com as conversões de geom existentes em plotly.R; considera-se concluído quando o exemplo não emitir mais avisos e renderizar contornos de densidade 2D preenchidos.