Slight changes to Packages files

[Ian Jackson <ian@chiark.chu.cam.ac.uk>]

This will primarily be of interest to the maintainers of dpkg-ftp and
dftp.

When packages are split on the FTP site all the relevant filenames
will be listed in the Filename field of the Packages files, separated
by spaces.

The size and md5sum fields will likewise contain lists of sizes and
md5sums.

I intend to introduce a new msdos-filename field giving the location
of the file in the msdos hierarchy (this will be used by dpkg's
Pre-Depends installation ordering mechanism).

Ian.