Modularised dispatch (#95)

* Completely rework dispatch mechanism into something modular.

Not yet complete but 75% there.

* Council vote tests.

* Fix tests.

* whitespace.

* Fix demo runtime tests.

* Fix up tests.

* Remove dead code.

* Use match for Id

* Make PrivPass better protected.

* Address other grumbles.

* Give PrivPass a private member.

* Testing PrivPass.

* Add docs.