Deprecating ftpd in the FreeBSD base system?

[Ed Maste]

FTP is (becoming?) a legacy protocol, and I think it may be time to
remove the ftp server from the FreeBSD base system - with the recent
security advisory for ftpd serving as a reminder.

I've proposed adding a deprecation notice to the man page in
https://reviews.freebsd.org/D26447 to start this off. There are a
number of ftp servers in ports, and if we're going to remove the base
system one we can create a port for it first, as well.

Any comments or concerns, please follow up in the code review or in email here.