This commit improves some FTP implementation details for better
compatibility with FTP clients:
* The PWD command now puts quotes around the directory name before
returning it. This fixes BBEdit’s FTP client, which performs a PWD after
each CWD and gets confused if the returned directory path is not
surrounded by quotes.
* The FEAT command is now allowed before logging in. This fixes the lftp
client, which send FEAT first and gets confused (tries to use TLS) if the
server responds with 332.
342dc61784