SQL Patch Version 2

Hunter,

Here is the latest patch for a SQL backend.

Fixed the docs a little.
Fixed several queries that were missing active=1.
Made rpm headers cached per channel.

I think I am happy with it for now. Until new functions are added.  Not perfect 
but seems to work ok.  Still several things that could be done to speed up most 
common lookups, if needed.  It can do about 500 rpm lookups per second on my 1 
GHz PIII.  That's with all of Redhat 7.1, 7.2 and errata in database.


Toby