security/ftpmap: Identify remote FTP server software by fingerprinting

Ftpmap scans remote FTP servers to indentify what software
and what versions they are running. It uses program-specific
fingerprints to discover the name of the software even when
banners have been changed or removed, or when some features
have been disabled. IPv6 is fully supported.

PR: ports/48899
Submitted by: Sergei Kolobov <sergei@kolobov.com>