build compressed tarballs for all of the IOCCC

Folded `all/README.md` into top level `README.md`.
Removed `all/summary.txt`.
Moved from `all/all.tar.bz2` to `ioccc.tar.bz2`.
Removed the `all/` directory.

Added `bin/tar-all.sh` form a compressed tarball for an IOCCC year:

```sh
bin/tar-all.sh -v 1 -W
```

Improved `bin/gen-years.sh`.

Added `make form_all_tarball` to `make quick_www` and `make www` in the top level Makefile.

Performed `make www` given the above.  Some entry compressed tarballs
were updated due to recent updates.

years.html

@@ -105,8 +105,8 @@
 <h1 id="ioccc-winning-entries-by-year">IOCCC Winning Entries by
 Year</h1>
 <h2 id="all-ioccc-years">All IOCCC years</h2>
-<p><strong>Download IOCCC</strong> <a href="all/ioccc.all.tar.bz2">all
-entry source</a></p>
+<p><strong>Download IOCCC</strong> <a href="ioccc.tar.bz2">all entry
+source</a></p>
 <h3 id="jump-to">Jump to:</h3>
 <p><a href="#2020">2020</a> | <a href="#2019">2019</a> | <a
 href="#2018">2018</a> | <a href="#2015">2015</a> | <a