Unknown method handling in squid 2.x

Here are two patches against squid 2.HEAD.

The first completely changes the nature of method_t in order to allow
squid to pass through methods it doesn't know about. What is
currently called method_t becomes method_code_t and method_t becomes a
structure containing a method_code_t and a string for the method
itself. We have a bunch of pre-allocated method_t's for methods we
know about and any method we don't know about ends up with a code of
METHOD_OTHER and a specially allocated method_t.

The second patch builds on the first by adding proper purge behaviour
in response to unknown methods and methods that are specified as
causing object purges. Note that due to the variant purging patch
being backed out, variants are not purged at this time.

I've done some testing on this, and mnot has been using these as well.

I'll put these in bugzilla in a short while.

Please let me know if you have any feedback.

-- 
Benno Rice
benno_at_jeamland.net