Cosmetic fix.
Under -S, show the size of the Bloom filter type.
Remove comment made obsolete by Bloom filtering.
Package node-list context into a sttruct.  All regression tests pass.

The eventual goal is to be able to use more than one of them in different
parallelized threads.  We can't do that yet because a Bison parser
doesn't yet make a thread-safe runtime.
Eliminate a global. All regression tests pass.
No longer necessary, and probably not desirable, to playy with ancient YACC.
Make the master-file parser re-entrant.
Eliminate void pointers. All regression tests pass.
Each cvs_file context carries its own node hash now.

This eliminates a global.

All regression tests pass.
Reduce exposure of a global. All regression tests pass.
Cleanup. All regression tests pass.
User flex --header-file ro eliminare some hand-rolled code.

All regression tests pass.
Ignore another generated file.
Reduce this_file's visibility.  All regression tests pass.
Remove a redundant declaration.
We're welded to flex/bison by the reentrancy requirement...

...so optomize the Makefile and filenames.

All regression tests pass.
Cosmetic rearrangement.  All regression tests pass.
At last, a fully re-entrant parser and lexer.

All regression tests pass.
Cosmetic cleanup.  All regression tests pass.