Wallet stuff

I wasn't sure whether or not to PR this. I decided to go ahead and make the PR, because the changes are pretty dramatic and I don't like making moster PRs, and giving this one more time to cure would probably increase the complexity of the PR.

Tons of tiny fixes that I did as they made sense. Added tags to the makefile which means we don't need separate code in our release branch - it can be the master code it's just frozen at whatever commit the master branch was at.

I went ahead and changed the structure of ArbitraryData, which fixes #168 (closed)

And then I turned wallet into a complex interface which makes up the bulk of the code in this PR. Eventually, the old wallet (which is still around) will be removed, but that's going to introduce probably a few hundred additional lines of change so I held off from adding it to this PR.

*tips fedora