Now I tested and discussed with claude, and had a working version of
this project.  The rest is to port the claude version to my own
writings.  So this serves as the starting point before that attempt.

In the new attempt the design is better, and a number of bugs were
found and supposedly fixed, so let us see how this goes at the end.

I think the main functionalities are already there, but the lack of
querying capabilities makes this not very useful at the moment.

This commit is right before an attempt to add this missing piece.

The purpose of this change is to share this trait with other crates,
such as the forth-coming "semiring" crate that will be responsible for
handling some simple semiring operations as well as the querying, in
my plans.

I have fixed another bug and think that the version of a more stable
version is worth bumping the versions for.

It seems to be complete now, but still awaits more tests to see where
the errors are, which should be plenty, haha.

Now the forest can detect if a node is packed or cloned, and correctly
clones a node in those circumstances.  But it still needs to be
tested.

I have an ostensibly working prototype now.

Further tests are needed to make sure that the algorithm meets the
time complexity requirement, though.

I seem to have finished the implementation of forests.  Now it remains
the implementation of the chain-rule machine, of which I have a rough
plan now.

Now the grammar will record the left-linear expansions when generating
the nondeterministic finite automaton frmo its rules, and will record
whether an edge in the nondeterministic finite automaton comes from a
left-linear expansion.  The latter is needed because while performing
a chain-rule derivation, we do not need the left-linear expanded
derivations in the "first layer".  This might well have been the root
cause of the bad performance of the previous version of this package.

Also I have figured out how to properly generate and handle parse
forests while manipulating the "chain-rule machine".

I am about to re-start my system, so I save before any crashes
happen.