Finally the prototype parser has produced the first correct forest.
It is my first time to generate a correct forest, in fact, ever since
the beginning of this project.

I have an ostensibly working prototype now.

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

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".