[PATCH] Enhanced access logging, added ICAP logging, bug #2495 fix.

This is the second part of the 3p1-plus patch. This patch include:

   - Enhanced access logging
     (<Hs, <sh, >sh, <pt, <tt, icap::total_time, and icap::<last_h)

   - ICAP logging
     (see icap_log and log_icap in squid.conf as well as
     http://wiki.squid-cache.org/Features/AdaptationLog).

   - ICAP retries based on the ICAP responses status code
     (see icap_retry and icap_retry_limit in squid.conf).

   - Support logging resp. times of adaptation transactions to access.log
     (%adaptation::sum_trs and %adaptation::all_trs)

   - Support logging of total DNS wait time to access.log
     (%dt)

   - Bug #2495 fix

Moreover it includes the following changes which requested by Amos:
    - the "Hs" formating code renamed to "<Hs"
    - The user still can use the "Hs" formating code but will see a
warning in his logs
   - s/LFT_LAST_MATCHED_ICAP_/LFT_ICAP_LAST_MATCHED/g
   - s/icap_/icap::/ in access log format codes only.
   - s/LFT_SENT_HTTP_CODE/LFT_HTTP_SENT_STATUS_CODE/ and
      s/LFT_RECEIVED_HTTP_CODE/LFT_HTTP_RECEIVED_STATUS_CODE/
   - Add support for "http::" prefix for access log format codes

I also have some questions to developers:
    - In squid.conf documentation I prepend each
      HTTP format code with [http::]
      Is it OK?

    - Should we replace icap::Hs with icap::<Hs ? Any opinion?
      (My opinion is we should not because the icap::>Hs does not make
sense)

I hope it is OK.
ouf...
Christos