Answering service doesn't properly prefix some messages during FTP login

[Eric Swenson]

The FTP protocol treats messages sent from the FTP server without a 3-digit prefix as errors. During login, the answering service engages with the client user to prompt for password and to emit login messages. Most messages are properly prefixed in lg_ctl_.pl1, however, there are a few that are missing the check for an FTP session, and the consequent required prefix.

Example messages are:

This is your 2nd login instance.
Your password was used incorrectly N times.