Kernels v2 (variable size) (#3034)

* wip

* exhaustive match

* write with fixed v1 strategy when writing for hashing

* local protocol version is 2

* cleanup "size" tests that exercise v1 vs v2 vs default protocol versions

* add proto version to Connected! log msg

* cleanup docs

* negotiate protocol version min(local, peer) when doing hand/shake

api/src/handlers/pool_api.rs

@@ -75,8 +75,8 @@ impl PoolPushHandler {
 						.map_err(|e| ErrorKind::RequestError(format!("Bad request: {}", e)).into())
 				})
 				.and_then(move |tx_bin| {
-					// TODO - pass protocol version in via the api call?
-					let version = ProtocolVersion::local();
+					// All wallet api interaction explicitly uses protocol version 1 for now.
+					let version = ProtocolVersion(1);
 
 					ser::deserialize(&mut &tx_bin[..], version)
 						.map_err(|e| ErrorKind::RequestError(format!("Bad request: {}", e)).into())