White space fixes (fixing over-long lines) in core files.
"Secure Mode" implemented. When this is enabled in john.conf, no
cracked password is ever printed, logged or stored in plaintext.
Instead you get an indication of length and use of classes. For
example, the password "Ignit3" would output as L6-?l?d?u telling
you that it's six characters long and consists of lowercase, digits
and uppercase characters.  This closes #505.