Notable changes:
* Rewritten transport protocols into Dialer and Listener (Nym is TODO)
This simplifies using the transports a lot, as can be seen for example
in src/rpc, and generally around the p2p library. It also defines features
for each transport (all of which are enabled by default). We drop the
socks client for Tor and Nym and use first-class support with the Arti Tor
library, and nym-sphinx/nym-websockets (to be used with nym-client).
* Outbound session healing
The outbound session will now poll and try to fill all the requested
slots more efficiently, and if needed, will activate peer discovery to
find more peers if we can't connect to any known ones. Also if we're
unable to connect to any, we shall drop them from our set.
Additionally, transport mixing is enabled by default, so when we're
allowing transport mixing, and we use Tor, we will also be able to connect
to other transports that Tor can connect to (e.g. tcp://).
* Unix socket transport dropped
We haven't been using this, and it seems we're not going down this path,
so the code has been obsoleted and removed.
* TLS session verification
We fully verify server and client TLS certificates upon connection so
we're able to perform TLS1.3 with forward secrecy.
* lilith pruning
lilith now periodically prunes known peers from its sets if it's unable
to connect to them.
This prevents double-voting in the sense of minting new coins _after_
a proposal was created, meaning only the coins that have existed prior
to creating a certain proposal are able to vote on it.
This is done by marking down the latest Merkle root in the Money state
and attaching it to the proposal's metadata. Then this root is used for
verifying inclusion proofs when voting.
