Make recursion optional

[courtiol]

Fixes #149

The idea of this PR is the reduce a little further the clutter while remaining accurate.
Here is an example with dplyr, a package with a lot of dependencies.
The basic plot is quite unreadable because it shows too much:

library(miniCRAN)
plot(makeDepGraph(pkg = "dplyr"))

The situation improves if suggested packages are turned off:

plot(makeDepGraph(pkg = "dplyr", suggests = FALSE))

But one could argue, do we really need here to show e.g. pkgconfig which is only on indirect dependencies (imported by tibble, which is itself imported by dplyr).

What I did was thus to refine the internal call to tools::package_dependencies() so as to exploit the argument it contains called recursive. It was hard-coded as TRUE but now the user can control it:

plot(makeDepGraph(pkg = "dplyr", suggests = FALSE, recursive = FALSE))

Note that contrary to the original argument recursive in tools::package_dependencies() which allows for both logical or character vector input, I restricted the use to a logical only. I explored the alternative but it would lead to quite a lot of changes in the code.

I paid attention to update the package examples, tests, news and description.

R CMD check does not complain about anything on my system.

[courtiol]

There are still glitches I am trying to solve...

[andrie]

I suspect the better way to do this is to compute on the dependency graph itself, rather than to limit recursion.

In igraph you can compute the shortest distance to a node: https://r.igraph.org/reference/distances.html?q=distance#null

It should then be possible to remove all nodes with a distance greater than n.

[courtiol]

Thanks @andrie, would you like to implement that?
It has been 2 years I submitted this so I forgot the structure of your package in the meantime and I don't know anything about igraph...