fix more broken markdown links

We fix more markdown links in markdown files that refer to files
internally to the web site.

Added tmp tools to find and print various markdown links:

* `tmp/md-links.sh` - print all markdown links
* `tmp/md-token-links.sh` - print all markdown links that start with a **%%TOKEN%%**
* `tmp/md-local-links.sh` - print all markdown links to a local file
* `tmp/md-link-paths.sh` - print local file paths referenced in markdown links

Fixed a number of markdown formatting problems with `thanks-for-help.md`.
Fixed markdown links to files in `thanks-for-help.md`.  Improved
heading levels in `thanks-for-help.md`, and made entry sections consistent.

Changed all markdown links that end in "))" to end in a better way.

Explained in `markdown.md` why we are avoiding markdown links that
end in "))".

Ran `make www` to perform the above.

TODO: Fix stuff we broke by mistake doing the above.

TODO: Fix more broken markdown links.

2005/toledo/README.md

@@ -68,14 +68,14 @@ get the first mode, run the program without arguments:
 ```
 
 The other mode is accessible running the program with one argument
-(5-[ply](https://en.wikipedia.org/wiki/Ply_(game_theory))
+(5-[ply](https://en.wikipedia.org/wiki/Ply_(game_theory))
 analysis):
 
 ``` <!---sh-->
     ./toledo a
 ```
 
-Two arguments for 6-[ply](https://en.wikipedia.org/wiki/Ply_(game_theory))
+Two arguments for 6-[ply](https://en.wikipedia.org/wiki/Ply_&#x28;game_theory&#x29;)
 analysis:
 
 ``` <!---sh-->
@@ -83,7 +83,7 @@ analysis:
 ```
 
 And each successive argument will analyze one
-[ply](https://en.wikipedia.org/wiki/Ply_(game_theory)) more. There is no ply
+[ply](https://en.wikipedia.org/wiki/Ply_&#x28;game_theory&#x29;) more. There is no ply
 limit, but beyond 7 ply is very slow, try it at your own risk and computing
 time.
 
@@ -125,7 +125,7 @@ algorithms.
 
 The interface accounts for only a fraction of the code, the core does multiples
 functions: it is called recursively to analyze and evaluate each
-[ply](https://en.wikipedia.org/wiki/Ply_(game_theory)), does [alpha-beta
+[ply](https://en.wikipedia.org/wiki/Ply_&#x28;game_theory&#x29;), does [alpha-beta
 pruning](https://en.wikipedia.org/wiki/Alpha-beta_pruning), move generation,
 machine playing, check detection, illegal move verification and does moves after
 they are verified.
@@ -142,7 +142,7 @@ Other features are:
 * [Checkmate](https://en.wikipedia.org/wiki/Checkmate) detection.
 * Stalemate detection.
 * Computer is tough (check
-7-[ply](https://en.wikipedia.org/wiki/Ply_(game_theory))) and even in 5 ply can give a surprise to
+7-[ply](https://en.wikipedia.org/wiki/Ply_&#x28;game_theory&#x29;) and even in 5 ply can give a surprise to
 amateur players.
 
 

2005/toledo/index.html

@@ -475,7 +475,7 @@ computer can do all legal chess moves.</p>
 <li><a href="https://en.wikipedia.org/wiki/Checkmate">Checkmate</a> detection.</li>
 <li>Stalemate detection.</li>
 <li>Computer is tough (check
-7-<a href="https://en.wikipedia.org/wiki/Ply_(game_theory)">ply</a>) and even in 5 ply can give a surprise to
+7-<a href="https://en.wikipedia.org/wiki/Ply_(game_theory)">ply</a> and even in 5 ply can give a surprise to
 amateur players.</li>
 </ul>
 <h3 id="obfuscation-tricks">Obfuscation tricks</h3>