IPv6: refresh options decoding (GH #47 pt. 3)

Brian Haley points that mobility (sub-)options decoded in
print-ip6opts.c are specific to draft-ietf-mobileip-ipv6 only. RFC3775
(and respectively RFC6275) uses different encoding and parameter space,
which print-mobility.c already handles.

Remove deprecated code and update some related macros.
added RPL decode for DAO and DAOACK, refactor out option printer
added decoding of RPL DAO and DAOACK sub-options
Merge branch 'master' of git+ssh://bpf.tcpdump.org/tcpdump/master/git/tcpdump
added test case for a DAO-ACK with no options
make sure that DAOACK option printer gets accurate length, and does not indicate truncated spuriously
RPL: test data and fix for printing DAO messages
RPL: rename test case files to be more clear as to their purpose