auto expiring object store

[Marco d'Itri]

http://www.swelltech.com/pengies/joe/squidng.html

It's designed for squid, but looks like it will work fine with a
slightly mutated tradspool storage method.

Objects are accessed by a 64 bit number which could go straight in the
history DB.

Optionally, when used disk space goes over a threshold, older objects
will be garbage collected.

When a object is created, an expire time can be specified.
Each object has a 32 bit opaque attribute applications can use for
their own needs.

-- 
ciao,
Marco