Use {conflicted} for R pkg conflict resolution

[pdiakumis]

Good to use this in the Rmd. From the https://github.com/r-lib/conflicted README:

library(conflicted)
library(dplyr)

filter(mtcars, cyl == 8)
#> Error:
#> ! [conflicted] filter found in 2 packages.
#> Either pick the one you want with `::`:
#> • dplyr::filter
#> • stats::filter
#> Or declare a preference with `conflicts_prefer()`:
#> • `conflicts_prefer(dplyr::filter)`
#> • `conflicts_prefer(stats::filter)`

[pdiakumis]

Done via #88.