Change the `Container.serialize` interface so that it is possible to
supply a list of objects that will be serialized instead of all the ones
in the container.
Overhaul the logic and method names involved in enabling and disabling
reference caching in `TupleTree<T>`. `TupleTreeReference<T, U>` now
lazily caches the target and will traverse the path only when needed.
Also expose and use these functions in the new pipeline, which should
provide some speedup when executing a `Schedule`.
Add the functionality the the pipeline infrastructure and CLI to run
individual pipe and analyses as subcommands instead of in-process. This
allow better debuggability of individual pipes.
Giacomo Vercesi