More html files of 2004 fixed

Some bug statuses have been changed so the bugs file was also updated
(some removed, some added).

The manifest of 2004/hibachi was fixed some.

The alt_url of 2004/gavare was fixed which required a rebuild of
authors.html.

For 2004/gavin a proper link to QEMU was added. It strikes me as it
possibly being a good idea to have an FAQ about QEMU (as it is not just
2004/gavin that might benefit from it) but I don't know and in any case
I have zero experience with it.

The entries 2004/gavare, 2004/gavin and 2004/hibachi have been checked
for format / display issues. This would suggest that the next entry to
look at is 2004/hoyle.

author/Anders_Gavare.json

@@ -7,7 +7,7 @@
     "location_code" : "SE",
     "email" : "gavare@gmail.com",
     "url" : "https://gavare.se",
-    "alt_url" : "https://gavare.se/ioccc/ioccc_gavare.c.html",
+    "alt_url" : "https://gavare.se/ioccc",
     "deprecated_twitter_handle" : null,
     "mastodon" : null,
     "mastodon_url" : null,