OPENDNSSEC-629: retransfer <zone>

New feature: ods-signer retransfer <zone>
Retransfers the zone with an AXFR from the master, ignoring the current inbound serial.
since n >= 10: n can be 10 and below chars in pos 11 and 12 are used, this may cause segfault.

probably same in all the other function checks.