feature request: caching

[Mark Moll <mmoll@cs.cmu.edu>]

One way to improve the performance of nnimap is to have a local cache of
mail folder information. This cache could contain:

1. .overview type of information
2. whole articles (possibly compressed; reading compressed articles from
   local disk is probably still faster than fetching the article from the
   server)
3. a combination of 1. and 2.

Ideally, what is cached and how much can be specified by the user. Any
comments?

-- 
Mark