Specify the signature of the DeleGate to be shown to client or server.
The full form signature "Version.Revision.Patch (Month Day, Year)" is
represented as "V.R.P/Y.M.D". To hide the a specific part, replace the
corresponding character with "x". For example, DGSIGN="V.x.x/Y.x.x"
will make signature like "DeleGate/9.x.x (x x, 2005)".