Ubuntu Ns-3 issues with Vector addition

Depending on the libraries at hand, adding Vectors is problematic. I have
made the addition more explicit so as to reduce errors when switching from
Debian to Ubuntu.
NNNAddress checks, isTopLvl, isEmpty boolean issues

I finally tested NNNAddress creation and ran into a lot more issues that I
expected. This was due to my lack of practice with iterators, making the
NNNAddress creation enter into a beautiful loop which consumed all the RAM on
my machine.

With that, I also check for double dots and empty dots within the NNNAddress
creation to try to minimize errors.

I re-implemented isTopLvlSector to make more sense. A similar function for
blank addresses is in isEmpty.

Finally there were some boolean returns that didn't make sense and have now
been simplified to make more sense.