[PATCH] Bug 1488: squid_status ACL

This updates and completes the work started by Gonzalo Arana in creating
an ACL to match the TCP_HIT, TCP_MISS, etc internal status of request
handling.

Requests can change their status over the course of a transaction.
Particularly around retries and revalidations. This ACL seeks to match
the current state as of the point of testing. The most reliable place is
of course in the logging ACL tests after any state changes have stopped.
Although any point after parsing may match on a relevant status.

To support this the squid status enum and supporting functionality is
also moved into its own file.

NOTES:
  At this point I'm not sure the main code is updating the status
correctly at all points it should change. Deferred that large audit task.

  There is also some questions about the states currently described vs
the ones that exist in Squid. ie should the enum be extended to a larger
set with the full state permutations, or split into a bitmap that can
support match on a subgroups of states (ie all HIT, all REFRESH)

Amos

-- 
Please be using
   Current Stable Squid 2.7.STABLE9 or 3.1.14
   Beta testers wanted for 3.2.0.10