fix many internal links

Fixed a number of internal links that need to
go to the GitHub site.

Ran `make www` to perform the above.

2018/index.html

@@ -411,7 +411,7 @@ and 22 (one third of 666).</p>
         Identifying yourself, in an obvious way in your code, data, remarks
         or program output, unless you are Peter Honeyman or pretending
         to be Peter Honeyman, will be grounds for disqualification of your entry.</code></pre>
-<p>A number of other entries were based on <a href="iocccsize.c">iocccsize.c</a>, making
+<p>A number of other entries were based on <a href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/2018/iocccsize.c">iocccsize.c</a>, making
 derivative works rather than original works.</p>
 <p>Still other entries were too large, violating the first line of rule 2:</p>
 <pre><code>    2) The size of your program source must be &lt;= 4096 bytes in length.</code></pre>