vchoi_fork

[svn-r4643] Purpose:
    Code cleanup
Description:
    Windows is generating hundreds of warnings from some of the practices in
    the library.  Mostly, they are because size_t is 32-bit and hsize_t is
    64-bit on Windows and we were carelessly casting the larger values down to
    the smaller ones without checking for overflow.

    Also, some other small code cleanups,etc.

Solution:
    Re-worked some algorithms to eliminate the casts and also added more
    overflow checking for assignments and function parameters which needed
    casts.

    Kent did most of the work, I just went over his changes and fit them into
    the the library code a bit better.

Platforms tested:
    FreeBSD 4.4 (hawkwind)