[development] Object caching

[Moshe Weitzman]

> There was interest in having it and then it seems the feeling was it's 
> complex.  the Caching API allows modules to implement a cache.  However, 
> the real benefit of file based caching is 1) Use lightweight webservers 
> threads to serve files 2) Don't need to bootstrap Drupal 3) Don't need 
> an expensive MySQL thread.
> 
> Keep asking for it and it's more likely to get in since the code is 
> available to be patched against head.

the consensus was that we would make core flexible enough such that this 
functionality can grow in Contrib for a while. At this point, I think effort 
is best expended in changing this code from a patch and into a Contrib 
cache.inc.