Squid commloops project

This project is aimed at reorganising the squid internals to provide a more flexible, intuitive and much faster IO model.

After a good 18 months of playing around with various optimisation ideas, I've settled on this plan:

• Remove the range request handling code inside client_side.c (DONE)
• Remove 'seen_offset' as a parameter to storeClientCopy() (DONE)
• Modify all of the storeClientCopy() callers to treat the call as a stream, by setting sequential/incrementing values of copy_offset
• Remove copy_offset from storeClientCopy(), turning it into a datastream-providing function, a la storeAppend()
• Add a flag to the storeClientCopy() callback to indicate an EOF condition (rather than checking the mem_obj->inmem_hi variable)

Once this is done, I'll re-evaluate the client<->server data flow model, since I would like to push the multiple-storeclient code into the storage FS layer and have the squid storage manager deal with a single client to server mapping. This will drastically reduce the amount of code required for the server/client flow, and hopefully help along the implementation of an improved network IO layer.