Elimination of (more or less) all compilation warnings on OSX

Hi all,

Before beginning my real quest for odbc, please find attached a patch
that cleans up 99% of the code warnings I saw on OSX (and actually
some of them on Windows). All those warnings are caused by incorrect
casts, so fixing them is trivial... But there were quite a lot of
them, I think I fixed 100~200 of them...
Then why 99%? I am still seeing exactly 4 warnings in socket.c caused
by some deprecated functions in openssl for OSX. I'll come back to
that later.
The patch is 160kB, so I had to compress it to bypass the ML restrictions.
Regards,
--
Michael