Added the ability to throw an error

example/site/index.html

@@ -4,3 +4,4 @@
 
 <a href="blog/2022-1-25.html">2021-1-25</a>
 <a href="blog/2022-1-31">2021-1-31</a>
+<a href="blog/forbidden">The forbidden blog post</a>

example/sitefile

@@ -6,6 +6,7 @@ define timeout 2000
 set host localhost:8000
 read / site/index.html
 read /hello  site/hello.html
+throw /blog/forbidden 403
 exec /blog/2022-1-31 site/blog/blog/2022-1-31.sh
 read /blog/.* site/blog/
 #/blog/2021-1-25.html turns into site/blog//blog/2021-1-25.html