Prevent crash in the case of a particular kind of broken nameserver.
Test for NO_RESPONSE_PTR_QUERY.
Add NO_GLUE, NO_GLUE_PREVENTS_NAMESERVER_TESTS, HAS_A_RECORDS and A_QUERY_NO_RESPONSES.
Add NAMESERVER_NO_UDP_53 and NAMESERVER_NO_TCP_53.
Add SOA_NOT_EXISTS and IS_NOT_AUTHORITATIVE.
Add EDNS0_BAD_QUERY, EDNS0_SUPPORT, QUERY_DROPPED, ANSWER_BAD_RCODE, CAN_BE_RESOLVED.
Add NO_RESPONSE_SOA_QUERY and NO_RESPONSE_MX_QUERY.
Merge pull request #204 from cdybedahl/add-todo-tests