add proof-manipulation to Lurk CLI

[porcuquine]

Something like the following should work:

% lurk prove program.lurk
% lurk verify proof.out
% lurk inspect proof.out

or

% lurk prove program.lurk -o proof.π
% lurk verify proof.π
% lurk inspect proof.π

[porcuquine]

This can and probably should integrate with the protocol API (i.e. defprotocol) — which may require a bit more machinery than I wrote above.