Advance coordinator implementation

- Common
	- Move ErrTODO and ErrDone to common for usage where needed.
- Coordinator
	- Move prover types to prover package
	- Handle reorgs, stopping the pipeline when necessary
	- Handle ethereum transaction errors by stopping the pipeline
	- In case of ethereum transaction revert, check for known revert causes
	  (more revert causes can be added to handle more cases)
	- Fix skipped transactions in TxManager confirmation logic
	- Cancel and wait for provers to be ready
	- Connect L2DB to:
		- purge l2txs due to timeout
		- mark l2txs at the different states
	- Connect HistoryDB to query L1UserTxs to forge in an L1Batch
- L2DB
	- Skip update functions when the input slices have no values (to avoid a
	  query with no values that results in an SQL error)
- StateDB
	- In LocalStateDB, fix Reset when mt == nil
- Prover (new package)
	- Rename the interface to Prover
	- Rename the mock struct to Mock
	- Extend Prover interface methods to provide everything required by the
	  coordinator
	- Begin implementing required http client code to interact with server
	  proof (not tested)
- Synchronizer:
	- Add LastForgeL1TxsNum to Stats
- Test/Client
	- Update Auction logic to track slots in which there's no forge during
	  the time before the deadline (following the solidity implementation)

db/l2db/l2db.go

@@ -177,6 +177,9 @@ func (l2db *L2DB) GetPendingTxs() ([]common.PoolL2Tx, error) {
 // StartForging updates the state of the transactions that will begin the forging process.
 // The state of the txs referenced by txIDs will be changed from Pending -> Forging
 func (l2db *L2DB) StartForging(txIDs []common.TxID, batchNum common.BatchNum) error {
+	if len(txIDs) == 0 {
+		return nil
+	}
 	query, args, err := sqlx.In(
 		`UPDATE tx_pool
 		SET state = ?, batch_num = ?
@@ -197,6 +200,9 @@ func (l2db *L2DB) StartForging(txIDs []common.TxID, batchNum common.BatchNum) er
 // DoneForging updates the state of the transactions that have been forged
 // so the state of the txs referenced by txIDs will be changed from Forging -> Forged
 func (l2db *L2DB) DoneForging(txIDs []common.TxID, batchNum common.BatchNum) error {
+	if len(txIDs) == 0 {
+		return nil
+	}
 	query, args, err := sqlx.In(
 		`UPDATE tx_pool
 		SET state = ?, batch_num = ?
@@ -217,6 +223,9 @@ func (l2db *L2DB) DoneForging(txIDs []common.TxID, batchNum common.BatchNum) err
 // InvalidateTxs updates the state of the transactions that are invalid.
 // The state of the txs referenced by txIDs will be changed from * -> Invalid
 func (l2db *L2DB) InvalidateTxs(txIDs []common.TxID, batchNum common.BatchNum) error {
+	if len(txIDs) == 0 {
+		return nil
+	}
 	query, args, err := sqlx.In(
 		`UPDATE tx_pool
 		SET state = ?, batch_num = ?
@@ -236,6 +245,9 @@ func (l2db *L2DB) InvalidateTxs(txIDs []common.TxID, batchNum common.BatchNum) e
 // CheckNonces invalidate txs with nonces that are smaller or equal than their respective accounts nonces.
 // The state of the affected txs will be changed from Pending -> Invalid
 func (l2db *L2DB) CheckNonces(updatedAccounts []common.Account, batchNum common.BatchNum) (err error) {
+	if len(updatedAccounts) == 0 {
+		return nil
+	}
 	txn, err := l2db.db.Beginx()
 	if err != nil {
 		return tracerr.Wrap(err)
@@ -261,7 +273,7 @@ func (l2db *L2DB) CheckNonces(updatedAccounts []common.Account, batchNum common.
 			return tracerr.Wrap(err)
 		}
 	}
-	return txn.Commit()
+	return tracerr.Wrap(txn.Commit())
 }
 
 // Reorg updates the state of txs that were updated in a batch that has been discarted due to a blockchain reorg.
@@ -312,5 +324,5 @@ func (l2db *L2DB) Purge(currentBatchNum common.BatchNum) (err error) {
 	if err != nil {
 		return tracerr.Wrap(err)
 	}
-	return txn.Commit()
+	return tracerr.Wrap(txn.Commit())
 }