Author: Alex Rousskov <rousskov@measurement-factory.com>, Christos Tsantilas <chtsant...

Author: Alex Rousskov <rousskov@measurement-factory.com>, Christos Tsantilas <chtsanti@users.sourceforge.net>
Added %err_code and %err_detail logformat codes to record details about transaction failures

For example, when Squid responds with 500 Internal Server Error, it is often
useful to know what went wrong.

This patch :
 - log a detail string instead of numbers for common errors
 - log a label with the detail code number for generic errors (system errors,
   or exceptions)
 - adds more details about errors, especially those detected with exceptions:
   We record a hash of the filename and the source code line number of the
   first caught exception.
 - adds two scripts which can help the developers to find the exact position
   of the caught exception:
   1) The calc-must-ids.pl take as argument one or more files and compute for
      each Must expression in the given files its  id;
   2) The calc-must-ids.sh can be used to find the exact position of a Must
      expression from its id. Example usage:
          # ./scripts/calc-must-ids.sh 0xB79EF14
          ./src/adaptation/ecap/MessageRep.cc:356: 0xB79EF14 Must(false);