Updated standalone nonterminal partitioning

- Started unifying names
- Fixed naming in 'business logic' layer
- Updated checker and verifier implementations
- Fixed some incorrect error messages in tests

Also fixed a peculiar issue with matching in common utilities.
The thing is, (a ... . d) actually matches _everything_, at least
with Chibi. I am even in doubt whether this is a legal pattern.

It _should_ match this pattern:

  (<pattern> ... <pattern> <ellipsis> <pattern> ... . <pattern>)

like this:

  (                  a         ...                  .     d    )

which is equivalent to

  (   P1 ... Pk      Pe    <ellpsis>   Pm+1 ... Pn  .    Px    )

with k, m, n all equal zero and thus Px matching anything.

I guess the reason is in the official definition of 'improper list'
as 'anything that is not a proper list' where a 'proper list' is
either an empty list, or a pair which cdr is a proper list. Thus,
_technically_ anything can be treated as an improper list, without
it being a pair. So a proper way to match improper list is this:
(x y ... . d).
Updated extension nonterminal partitioning

- Reimplemented addition, removal, and modification using
  new verifiers and new syntax for predicates and modifications.
- Updated the 'business logic' layer accordingly.
- Fixed misc helpers, squashers, etc.
- Fixed some incorrect expectations in tests.
s/description/definition/ for nonterminals

To be consistent with documentation. See commit 790a0cbc48
Merged branch 'partitioning-nonterminals' into 'partitioning'

~ All tests now pass! Yay! ~

Now I am going to do some cleanup, restructure, etc. to make the code
look somewhat better. After that this branch can be merged into master
(at last!)

Side goal: look into the slowness of tests, try starting Np tests on
some other implementation after writing a R7RS -> R6RS porter script.
I believe Chez is the right choice, its expander is blazing fast
according to the reports. I want to see whether this is an inherent
slowdown of CK-style macros, or just Chibi's expander being a slowpoke.
This will be also needed to compare Np with the original Nanopass from
Andy Keep. I am curious to see how bad am I doing compared to it, in
future.