Add "Samba Server" group
Remove "FTP server", "Mail Server", "Office packages",
"MATE DE", "Xorg" groups
Change NetworkManager to Systemd-networkd

Made at the request of Anton Abramov <abramovav@basealt.ru>

These have been:
- taken from x86_64 server iso (in substituted form);
- checked against m-p-d where needed;
- renamed from centaurus-* to centaurus/*;
- updated with s/samba-server/samba/;
- archdep bits adjusted for m-p-d/m-p syntax difference;
- amended with some tester feedback based additions included;
- pruned regarding p9/branch packages availability.