Add boost::archive as an alternative serialisation method

[hurufu]

It will be useful to exercise the possibility to change at compile time (or even at runtime) the ability to select different serialization methods. This may be needed in the future eg. due to licensing / performance issues. Code more or less is written with this modularity in mind, but this was never actually tested. The easiest way to exercise it to add very simple to use boost::archive serialization.