This fixes bugs in MB and CNAME.copy() (using sprintName for copying),
IPSECKEY (missed copyIP) and OPT (partially, Options was not copied as
slice; EDNS0 objects themselves are still pointers).
This process probably fixes a bug in NSAPPTR.len(), after a similar one was
found in HINFO.len().
This should also make it easier to make changes to these functions, and
check their correctness.
Generate the code by running "go generate".