Implements support for the compresion scheme used in binary DNS
messages.
This makes it possible to decode messages entirely, but not yet
actually resolve the labels to their "real" values.
All qnames are stored with file-offsets pointing at the position at
which their reading started, which enables the implementation of a
function to resolve pointers internally.
Adds a struct that represents QNAMEs, tracks the stream offset at
which the QNAME parsing began and makes it possible to resolve
pointers inside of the QNAME.
Note that resolving pointers needs to happen *after* the call to
lisp-binary currently. It might be possible to implement this inside
of lisp-binary in the future by switching on the top two bits of the
qname field, but since this is happening *inside* of a reader function
I'm not currently sure how to implement it.
This uses lisp-binary to define serialisation types for the DNS
messages defined by RFC 1035.
Currently the compression scheme used for QNAMEs is not supported,
hence deserialisation of even simple records fails after the header
and question sections are read.
