Fixes#3289.
This commit adds back the bit-struct library because in the end,
it is useful for some modules, especially pello's. It's small
and it has a nice license, so why not. After all, it /is/
useful for quicky application headers. Eventually, should
be replaced by StructFu, but that requires some doc work
on my part to get that transition in place.
This also adds pello's DNS fuzzer module which makes use of
BitStruct to create sometimes malformed-on-purpose DNS headers.
Tested against 3 different DNS servers, caused one to reboot,
so I'd say it works.
Tod Beardsley