Add option parser to rbldns-data

Introduced option parsing support in 'rbldns-data' tool. This helps
to have a consistent user interface across all 'ndjbdns' tools.
Also enables us to add new options if required and suppresses
compiler warning about unused parameter - 'argc'.

Did minor change to 'rbldns' server to suppress compiler warning
about an unused parameter: 'ip'.
Format sources for better readability and editing

Changed 'axfr-get' to format it for better readability and editing.
Introduced support of an option parser. It helps to have a
consistent user interface across all 'ndjbdns' tools. Also helps
to suppress compiler warning about unused 'argc' parameter.