[MERGE] config.h renaming to squid.h

As discussed today with Amos, here's the merge bundle for:
- renaming squid.h to squid-old.h
- renaming config.h to squid.h
- reconnecting things

This ipatch will avoid name clashes on Windows (and probably also
MacOS) between config.h and various Config.h files scattered in the
source-factor'ed subtrees (case insensitivity..)

-- 
    /kinkie