Minimal Transaction Pool (#1067)

* verify a tx like we verify a block (experimental)

* first minimal_pool test up and running but not testing what we need to

* rework tx_pool validation to use txhashset extension

* minimal tx pool wired up but rough

* works locally (rough statew though)
delete "legacy" pool and graph code

* rework the new pool into TransactionPool and Pool impls

* rework pool to store pool entries
with associated timer and source etc.

* all_transactions

* extra_txs so we can validate stempool against existing txpool

* rework reconcile_block

* txhashset apply_raw_tx can now rewind to a checkpoint (prev raw tx)

* wip - txhashset tx tests

* more flexible rewind on MMRs

* add tests to cover apply_raw_txs on txhashset extension

* add_to_stempool and add_to_txpool

* deaggregate multi kernel tx when adding to txpoool

* handle freshness in stempool
handle propagation of stempool txs via dandelion monitor

* patience timer and fluff if we cannot propagate
to next relay

* aggregate and fluff stempool is we have no relay

* refactor coinbase maturity

* rewrote basic tx pool tests to use a real txhashset via chain adapter

* rework dandelion monitor to reflect recent discussion
works locally but needs a cleanup

* refactor dandelion_monitor - split out phases

* more pool test coverage

* remove old test code from pool (still wip)

* block_building and block_reconciliation tests

* tracked down chain test failure...

* fix test_coinbase_maturity

* dandelion_monitor now runs...

* refactor dandelion config, shared across p2p and pool components

* fix pool tests with new config

* fix p2p tests

* rework tx pool to deal with duplicate commitments (testnet2 limitation)

* cleanup and address some PR feedback

* add big comment about pre_tx...

servers/src/mining/mine_block.rs

@@ -28,7 +28,6 @@ use common::adapters::PoolToChainAdapter;
 use common::types::Error;
 use core::consensus;
 use core::core;
-use core::core::Transaction;
 use core::core::hash::Hashed;
 use core::ser;
 use core::ser::AsFixedBytes;
@@ -163,8 +162,6 @@ fn build_block(
 		.unwrap()
 		.prepare_mineable_transactions(max_tx);
 
-	let txs: Vec<&Transaction> = txs.iter().collect();
-
 	// build the coinbase and the block itself
 	let fees = txs.iter().map(|tx| tx.fee()).sum();
 	let height = head.height + 1;