Add Debian packaging

[OddBloke]

This adds some basic Debian packaging. It will require a bit of time spent to work out how to build it outside of my environment (and if we are going to seriously consider Debian packaging it then we should probably split the packaging out to a separate branch).

[txels]

Thanks for this. I spent a very short while trying to figure out how to build it but no success. Any hints?

[OddBloke]

I was building it with git-buildpackage --git-upstream-tree=branch --git-upstream-branch=origin/master. Potentially if you tag 0.4.6 (I think), and then use git-buildpackage --git-upstream-branch=0.4.6 then it might work. It, by default, looks for the upstream/VERSION tag, so you could also do something with that.