Fix for certain FTP clients sending PORT commands

[dartonw]

Some FTP clients (CuteFTP is one, I believe) send
leading zeros in the IP portion of the PORT command,
e.g. "PORT 001,002,003,004,13,79". When an ip address
in this format (001.002.003.004) is passed to inet_addr
(), it is interpreted as octal. If 8 or 9 are present in the
IP, inet_addr() returns INADDR_NONE, and the PORT
command fails. This fix resolves that issue by converting
each octet of the IP to int and back to char to strip
leading zeros.

[dartonw]

inet_addr patch to ControlSocket.cpp

[Tim Kosse]

Applied heavily modifed patch. Please make sure NOT to
introduce buffer overflows: The size of the number passed to
itoa wasn't checked. PORT 01234,0,0,0,0,0 did at best crash
the entire server.

[dartonw]

Good point. I didn't account for malicious intent by users
sending literal commands.