[MERGE] String-Fix, second round

Hi all,
   here's a new round of merge (possibly the final one) of the
string-fix branch.

Summary of changes:
- finished the analysis of raw buffer exporting, divided among c-sting
and raw-buf access clients
- general sanitization
- reversal of some wrongly-renamed variables and comments
- implementation of SQUIDSTRINGPRINT and SQUIDSTRINGPH (placeholder) macros and
    psize() function for printf-style calls
- implementation of, and migration to, String::size_type and String::npos
- de-inlining of pos(), rpos(), find() and rfind() calls
- implementation and use of a proper substr() call

I'll now focus on implementing in StringNg the lessons I've learned
from string-fix.

The patch has been build-tested on 32- and 64-bit linux, and I'm
running it to send this mail. It seems to be working...

-- 
    /kinkie