feature request

[Luis Villa]

Hey, Sam, others:
I don't know if this is already solved by the venus branch's design
(not, from what I can tell) but it would be nice if there was a way to
specify a maximum cache size, or at least, a maximum per-feed cache
size. I just had to grep in my cache, and noticed that the cache is
now 1/2G, with some caches having entries over a year old, which is,
you know, a little silly ;)

Thanks-
Luis