script to ~build out a list of lists

script to ~build out a list of lists

In particular, given a starting list, this computes the transitive closure
under the operations:
* get the lists this list owns
* get the lists this list contains
* (disabled) get the lists that contain this list

It allows specifying a list whose members should be skipped, as well.

The code is easy to configure for which of those operations to use, and
whether to do it recursively or not. At the moment, this isn't exposed to
the command line, though that would be a reasonable feature to add.