sample_evam should accept a data frame as input

[rdiaz02]

This currently does not work

d1 <- data.frame(From = c("Root", "Root", rep(c("A", "B"), 3)),
                              To = c("A", "B", rep(c("C", "D", "E"), c(2, 2, 2))),
                              Relation = rep(c("Single", "AND", "OR", "XOR"), rep(2, 4)),
                              Lambdas = c(0.7, 0.8, rep(c(0.9, 0.4, 0.5), c(2, 2, 2))))

sample_evam(d1)

And yet, the web app is doing something that seems to be just that.

So:

1. We should allow for that type of use in the R package
2. We should document it in the help of sample_evam
3. HESBCN_model_2_output should accept an empty parent_set argument, and generate it on the fly from the dag (we already have function parent_set_from_edges).

In the web app we are using function generate_sample_from_dag. (Called on click on "resample_dag")