Include library calls in backwards lineage

[blernermhc]

When producing a backwards lineage, it would be good to include the library calls for the libraries needed by the statements on the lineage. That would allow for just those statements to be re-executed.

[blernermhc]

The libs_used branch of provGraphR is able to determine which libraries are used in the lineage. We need help from rdtLite to find out where the libraries are loaded. Suggest adding a field to the library nodes containing the proc id where the library call occurs, if it exists. It might be loaded using :: syntax, in which case library is not needed, or it might be loaded inside a function or some other library code that we do not see, and would hopefully (!) be included in the lineage already, but is that guaranteed??