Ikiwiki should support pagination for index pages. Something like showing only 10 items on the first page, and then having the other items on the other pages.

Basically, the same page would be rendered multiple times:

- The index page: rendered normally, but item list is truncated to N items
- The separate pages: rendered with a slice of the item list containing N items (or less for the last page)

This I think breaks one major assumption: that source pages only generate one page in the output directory.
