processed John Dalbec's fix of 2000/dlowe

Updated `bugs.html` to reflect the fix of all known bugs in `2000/dlowe`.

Added thank you to John Dalbec in `thanks-for-help.md`.

Added processing of "%%REPO_TOP_URL%%" tokens to `bin/subst.default.sh`.

Updated `find-missing-links.sh` to not falsely report missing links
when a "%%REPO_TOP_URL%%" token is used.

Changed `bin/subst.default.sh` VERSION from "1.3.2 2024-08-05"
to "1.4.0 2025-04-16".

Changed `bin/find-missing-links.sh` VERSION from "1.1.1 2024-04-28"
to "1.2.0 2025-04-16".

Due to a `pandoc(1)` bug fix, `2011/fredriksson/index.html` and
`2012/kang/index.html` were modified.  The bug fix removed extraneous
whitespace that was previously introduced into HTML under certain
situations.  These 2 changes do **NOT** impact the way web browsers
render these pages, however.

Updated sitemap.

Tested the above via `make www gen_status gen_sitemap timestamp` on macOS.

status.json

@@ -1,7 +1,7 @@
 {
     "no_comment" : "mandatory comment: because comments were removed from the original JSON spec",
     "IOCCC_status_version" : "1.0 2024-03-09",
-    "contest_status" : "open",
-    "news_update" : "2025-03-15T22:16:27+00:00",
-    "status_update" : "2025-03-05T18:15:23+00:00"
+    "contest_status" : "pending",
+    "news_update" : "2025-04-16T16:35:11+00:00",
+    "status_update" : "2024-12-29T10:01:35+00:00"
 }