Removal of set_global_graph_attrs

[jeremiedb]

Removing set_global_graph_attrs resulted in a breakage of the MXNet library which was using that function. This has been patched with add_global_graph_attrs, though the nodes are now of fixed size rather than wrapping the text content. I assume this can be fixed by changing some other graph attributes?

Although MXNet library isn't on CRAN, could there be a way to be made aware of potential breaking changes prior to a cran release that defunct or change behavior of some function? Thanks!