Add support for bit64::integer64 colouring

[Alex]

Currently integer64 columns are not supported in colouring. Example:

library(mapdeck)

set_token("my_mapbox_token")

roads <- mapdeck::roads
roads$i64 <- bit64::as.integer64(seq_len(nrow(roads)))

mapdeck() %>% 
  add_sf(data = roads
         , stroke_colour = "i64")

gives error

Error in rcpp_path_geojson(data, l, geometry_column, digits, "path") : 
  Error in function boost::math::trunc<double>(double): Value inf can not be represented in the target integer type.

It would be good if colouring was supported.

[Dave]

Thanks - I've put this in colourvalues as that's where the underlying error comes from.