[m-dev.] I want to move and rename the dependency_graph module

[Zoltan Somogyi]

Paul, I assume that you want dependency graphs for the MLDS
so that you can implement tail recursion for mutually recursive tail calls.
Is this correct?

When you first proposed that a bit more than a year ago, you didn't give us
much detail about how you planned to do it. Perhaps you could do so now.
It is always better to agree on the design approach before coding.

Are you targeting all MLDS backends, or just C? And what mechanism
do you intend to use for parameter passing, and for telling the trampoline
which member of the clique, if any, to call next? There is more than one
possible choice for both those questions; which combinations have you
tested for performance? You said then you had a script to help you explore
the issue; could you send it to us?

Zoltan.