Word-Length Indexer

A modification to the indexer that sorts words based on length. This should make
searching a little bit more efficient. After the patch is applied, your old index
will be automatically converted to the new format (when you visit a page). The
new index format is:

1. Index files are stored in savedir/index
2. Word lists are stored as wlen.idx. This used to be word.idx.
3. Word indexes are stored as ilen.idx. This used to be index.idx.
4. The page list, page.idx, is simply copied to the new location.

Any plugins you have, such as the blog plugin, that read the index files need to
be updated.

darcs-hash:20061112194900-2b9f0-a975498ccf0a1d39c6df73b79bcd028d5e81c389.gz