We now switch to the `llvm::df_iterator` based `nodesBetween`
implementation.
This new implementation makes use of the idiomatic way of extending the
DFS implementation provided by LLVM, instead of rolling our custom
implementation for the `nodesBetween` algorithm.
We improve the `getBackedges` and `nodesBetween` helper functions that
can be used for backedge discovery and computation of all the nodes
reachable on all the paths defined between two nodes in a graph.
We build upon the `llvm::df_iterator` function, by customizing the visit
stack to perform the desired visits.
Implement a couple of restructure algorithms in a template manner, so
that they can be used with any data structure implementing
`GraphTraits`.
Test the algorithms using the `GenericGraph` data structure.
Andrea Gussoni