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)

node/node.go

@@ -21,6 +21,7 @@ import (
 	"github.com/hermeznetwork/hermez-node/db/statedb"
 	"github.com/hermeznetwork/hermez-node/eth"
 	"github.com/hermeznetwork/hermez-node/log"
+	"github.com/hermeznetwork/hermez-node/prover"
 	"github.com/hermeznetwork/hermez-node/synchronizer"
 	"github.com/hermeznetwork/hermez-node/test/debugapi"
 	"github.com/hermeznetwork/hermez-node/txselector"
@@ -162,9 +163,9 @@ func NewNode(mode Mode, cfg *config.Node, coordCfg *config.Coordinator) (*Node,
 		if err != nil {
 			return nil, tracerr.Wrap(err)
 		}
-		serverProofs := make([]coordinator.ServerProofInterface, len(coordCfg.ServerProofs))
+		serverProofs := make([]prover.Client, len(coordCfg.ServerProofs))
 		for i, serverProofCfg := range coordCfg.ServerProofs {
-			serverProofs[i] = coordinator.NewServerProof(serverProofCfg.URL)
+			serverProofs[i] = prover.NewProofServerClient(serverProofCfg.URL)
 		}
 
 		coord, err = coordinator.NewCoordinator(
@@ -173,6 +174,7 @@ func NewNode(mode Mode, cfg *config.Node, coordCfg *config.Coordinator) (*Node,
 				ConfirmBlocks: coordCfg.ConfirmBlocks,
 			},
 			historyDB,
+			l2DB,
 			txSelector,
 			batchBuilder,
 			serverProofs,