APIDump: Extra pages renamed to articles and moved to front.
APIDump: Split the huge DumpAPIHtml function into smaller ones.
APIDump: Added a quick-nav menu to class descriptions.

First part of #403.
APIDump: Added a quick-nav menu to hook descriptions.

Second part of #403.
APIDump: Added quick links to index to each class and hook file.

Third part of #403.