Add Hakyll site generator and assets

Add site executable and Haskell modules (site.hs, ChaoDoc.hs,
SideNoteHTML.hs, Pangu.hs) to handle Pandoc/Hakyll compilation,
theorem/sidenote processing and CJK spacing. Add CSS, font files,
favicon, templates, Makefile, and a CSL bibliographic style. Update
.gitignore to ignore build artifacts.

templates/post-list.html

@@ -0,0 +1,5 @@
+<ul class="post-list">
+    $for(posts)$
+    <li><a href="$url$">$title$</a></li>
+    $endfor$
+</ul>