Added "jgs" branch, containing jgs-style serialization in its own namespace

[Richard Schwarting <richard schwarting ca>]

I'll merge it with master once I get it compiling.

Daniel, if you'd like it to be merged sooner, so you can make sure your own changes don't break things, let me know.

Also, I realised that the serialization tests in test/ can be separated as well.  Whee.