#12 Cache system

At the moment I don't think Smarty's built-in cache
system will work. I can't add in userdata such as "You
are logged in as" because it uses what was cached, not
a version with new stuff added in. We need a way to
cache all BUT overall_header.tpl perhaps, or even do
that only for logged in users while guests get the full
cache.

However since Smarty will cache view.tpl as it is, that
means that every article will have the same cache. No
good. Needs modification bigtime.