improve years.html and fix links to year-level compressed tarballs

Fixed links to year level compressed tarballs.

Added an "Inventory" of year-level compressed tarballs to the
generated `years.html` web page.

In `bin/gen-years.sh` changed VERSION from "1.0.3 2024-03-26"
to "1.1 2024-03-30".

In `bin/output-year-index.sh` changed VERSION from "1.1.2 2024-03-26"
to "1.2 2024-03-30".

Added `inc/topnav.empty.html` for an empty narrow topnav bar.

Changed references from "topnav=." to "topnav=empty" in `inc/md2html.cfg`.

Removed top level `ioccc.tar.bz2` compressed tarball.  NOTE: Sorry
(tm Canada 🇨🇦) to remove the top level `ioccc.tar.bz2` file.  We
will look into [Git Large File Storage [Git-LFS](https://git-lfs.com/).
If Git-LFS works well and does not have undesirable side effects,
we will consider restoring `ioccc.tar.bz2`.

Removed top level Makefile rules for "untar_all_tarball" and
"form_all_tarball".  Removed `bin/tar-all.sh`.

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

Ran `make www` to perform the above and test under macOS.

CODE_OF_CONDUCT.html

@@ -48,6 +48,13 @@
 </div>
 
 <!-- END: this line ends content from: inc/header.default.html -->
+<!-- START: this line starts content from: inc/topnav.default.html -->
+
+<div class="topnav">
+&nbsp;
+</div>
+
+<!-- END: this line ends content from: inc/topnav.default.html -->
 <!-- START: this line starts content from: inc/begin-row.default.html -->
 
 <div class="row">