SMBAuth - Authenticate a user/password against an NT server

int auth(string username, string password, string server, 
	string backup, string domain)

authenticates username with password password against an smb server or
backup in domain domain. 

return codes:

0 - User authenticated successfully.
1 - Server error.
2 - Protocol error.
3 - Logon error; Incorrect password or username given.
