Refactor: reunite reveal messages

[h4sh3d]

Based on #742

This PR reunite the Reveal::Param and Reveal::Proof over one unique Reveal message.

The feature is build on Reveal2 type and all old Reveal code has been commented only, when tested I'll add a commit to remove the comments and clean up the new code.

[TheCharlatan]

This triggers

thread 'main' panicked at 'called `Option::unwrap()` on a `None` value', src/swapd/runtime.rs:719:73`

in the swap_bob_maker_user_abort_sweep_btc test.

[h4sh3d]

This triggers

thread 'main' panicked at 'called `Option::unwrap()` on a `None` value', src/swapd/runtime.rs:719:73`

in the swap_bob_maker_user_abort_sweep_btc test.

Fixed in a9d3e97

EDIT: full fix with 786ace2