* src/closure.h: New file.

* src/closure.h: New file.
* src/closure.c: Formatting changes, topological sort over the
functions, use of closure.h.
(initialize_closure, finalize_closure):  Rename as...
(new_closure, free_closure): these.  Adjust dependencies.
* src/LR0.c: Formatting changes, topological sort, use of
cloture.h.
(initialize_states): Rename as...
(new_states): this.
* src/Makefile.am (noinst_HEADERS): Adjust.