Many manifest improvements and fixes

This is a large update that modifies every .entry.json file and fixes
many others. The changes of every .entry.json file are as follows:

- change 'entry source' to 'entry source code' [0]
- change 'original source' to 'original source code' [0]
- change 'directory path from top directory' to 'directory path from top
  level directory'

[0] This is for consistency purposes. Other options were pondered but as
the index.html files refer to 'Alternate code' this was the simplest way
to go about it and it also feels more natural. A question was whether to
have 'entry code' and 'original entry code' or to have the word 'source'
added to it but I decided upon including the word 'source'. Another
question has occurred to me is whether or not 'original source code'
should instead be 'original entry source code' but that can be decided
upon later as that occurred to me after much of the files were already
rebuilt. The consistency that this commit has made is for the README.md
sections and in particular 'Alternate code'. One might wonder if that
should be changed to 'Alternate source code' as now the manifest
includes 'source' in the 'entry code' and 'original code' but the
manifest itself is what was actually updated and having 'source' feels
more natural for submitted files. After all not all entries have
alternate code. These questions can be decided on when looking at the
index.html files that have been rebuilt.

Changed 'alt code' to 'alternate code' where this was not already done
(in the manifest). It is questionable whether this should be done in
markdown files or not (in the README.md files section it already is done
but not necessarily in other places).

Many files had incorrect descriptions that have been checked.

Renamed 2020/endoh2/spoiler/spoiler.{md,html} to index.{md,html} so one
can go to just 2020/endoh2/spoiler and see the web page. Although the
manifest of 2 020/endoh2/index.html will link to it and that's probably
how most people will notice it it seems useful especially as the web
page links to the different files in spoiler/ or at least refers to
them, giving a description (kind of like the manifest in
2020/endoh2/index.html).

Due to the above changes all the entries had their index.html files
regenerated too.

There were likely other changes and fixes as well.

What has NOT been done is a check over all items, typos or otherwise,
though some typos have been fixed. Nonetheless this commit goes a long
way to resolving issue #1933.

Updated thanks file both with a missing <div> id and added a manifest
improvements section as the manifest is quite important.

1990/scjones/index.html

@@ -450,9 +450,9 @@ would allow for sequence numbers to be punched in columns 73-80 :-).</p>
 </div>
 <h2 id="primary-files">Primary files</h2>
 <ul>
-<li><a href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/1990/scjones/scjones.c">scjones.c</a> - entry source</li>
+<li><a href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/1990/scjones/scjones.c">scjones.c</a> - entry source code</li>
 <li><a href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/1990/scjones/Makefile">Makefile</a> - entry Makefile</li>
-<li><a href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/1990/scjones/scjones.orig.c">scjones.orig.c</a> - original source</li>
+<li><a href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/1990/scjones/scjones.orig.c">scjones.orig.c</a> - original source code</li>
 <li><a href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/1990/scjones/try.sh">try.sh</a> - script to try entry</li>
 </ul>
 <h2 id="secondary-files">Secondary files</h2>
@@ -461,7 +461,7 @@ would allow for sequence numbers to be punched in columns 73-80 :-).</p>
 <li><a href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/1990/scjones/README.md">README.md</a> - markdown source for this web page</li>
 <li><a href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/1990/scjones/.entry.json">.entry.json</a> - entry summary and manifest in JSON</li>
 <li><a href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/1990/scjones/.gitignore">.gitignore</a> - list of files that should not be committed under git</li>
-<li><a href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/1990/scjones/.path">.path</a> - directory path from top directory</li>
+<li><a href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/1990/scjones/.path">.path</a> - directory path from top level directory</li>
 <li><a href="index.html">index.html</a> - this web page</li>
 </ul>
 <hr style="width:10%;text-align:left;margin-left:0">