- Implement Pipeline.prepareForgeBatchArgs()
- Add a minimal stress test for the coordinator (that also runs the
  synchronizer)
- Update txprocessor.ProcessTxs() to return valid results for batches without
  transactions
  	- Add the boilerplate for the corresponding test, leaving as TODO the
	  zkInput values
- Update prover client to use the same point format as proof server (projective)
- Update interface of TxSelector.GetCoordIdxs to also return the authorizations
  to create accounts that go with the l1CoordinatorTxs.

Update usage of `*babyjub.PublicKey` to `babyjub.PublicKeyComp`
- when the key is not defined, internally is used `babyjub.EmptyBJJComp`, which is a `[32]byte` of zeroes of type `babyjub.PublicKeyComp`
- the API continues returning `nil` when the key is not defined

For the case of tx.EthAddr!=tx.FromIdx.EthAddr

- Update IntermediateState FinalAccFee values to fit in the Circom circuit expected inputs
- Add ZKInputs generation test with transactions generated by Til
(TestZKInputs6)
- BatchBuilder: remove redundant MakeCheckpoint call

- Update tx processor of Exit & ForceExit types
- Update ZKInputs generation related to Exit transactions
- Add TestZKInputs5 which adds tests generation of ZKInputs compatible
with Circom circuits including Exit (L2) & ForceExit (L1) transaction types
- Add StateDB test to check max DepositAmount case

- StateDB fix process txs of type CreateAccountDepositTransfer & DepositTransfer
- Add TestZKInputs3 & TestZKInputs4 which:
    - have a compatible check in js version to check Circom circuits
compatibility
    - adds test of tx type of CreateAccountDepositTransfer &
DepositTransfer

- add IntermediateStates AccFeeOut correct generation for circuits
compatibility at ZKInputs
- Fix formatAccumulatedFees
- organize ZKInputs tests to check compatibility with Circom circuits
- Add TestZKInputs2
    - which checks ZKInputs for 4 L1 txs + 2 L2Txs with fees
    - tested with Hermez Circom circuits

- Common
	- Add `IdxNonce` type used to track nonces in accounts to invalidate
	  l2txs in the pool
- Config
	- Update coordinator config will all the new configuration parameters
	  used in the coordinator
- Coordinator
	- Introduce the `Purger` to track how often to purge and do the job when
	  needed according to a configuration.
	- Implement the methods to invalidate l2txs transactions due to l2txs
	  selection in batches.  For now these functions are not used in favour
	  of the `Purger` methods, which check ALL the l2txs in the pool.
	- Call Invalidation and Purging methods of the purger both when the
	  node is forging (in the pipeline when starting a new batch) and when
	  the node is not forging (in coordinator when being notified about a
	  new synced block)
- L2DB:
	- Implement `GetPendingUniqueFromIdxs` to get all the unique idxs from
	  pending transactions (used to get their nonces and then invalidate
	  txs)
	- Redo `CheckNonces` with a single SQL query and using `common.IdxNonce`
	  instead of `common.Account`
- StateDB:
	- Expose GetIdx to check errors when invalidating pool txs
- Synchronizer:
	- Test forged L1UserTxs processed by TxProcessor
	- Improve checks of Effective values
- TxSelector:
	- Expose the internal LocalStateDB in order to check account nonces in
	  the coordinator when not forging.

- Separate ZKInputs tests at StateDB package
- Small fix at ZKInputs generation FeeIdxs length
- Fees related parameters at ZKInputs works properly
- Add ZKInputs generation test with fees (`TestZKInputs1`), which output
has been tested with circom to ensure compatibility

- Add SignatureConstant to L1Tx.TxCompressedData
- ZKInputs generation works initial version working and compatible with circom Hermez circuit
    - Lots of small updates for circuits compatibility
- Update version (with new changes) of `go-iden3-crypto` & `go-merkletree`

- Add InvalidData flag to L1Tx
- Add BytesDataAvailability to L1Tx
- Update ZKInputs & HashGlobalInputs to last spec of the protocol
(massive migrations)
- TxProcessor check correctness of L1Txs

Compatible with hermeznetwork/commonjs v0.0.4
(c345239bba)

- Add L1Tx TxCompressedData method
- Add PoolL2Tx TxCompressedDataV2 method
- Update ProcessTxs logic
- Add ZKInputs Intermediate States & Fee parameters calculation

Add HashGlobalInputs for ZKInputs compatible with js & circom circuits version.

Compatible with hermeznetwork/commonjs at version: c6a1448db5
(c6a1448db5)

- Allow starting the DebugAPI from the node via config
- In StateDB:
    - Make checkpoints when ProcessTxs() succeeds
    - Remove extra hardcoded `statedb` path that was redundant
    - Replace hardcoded `[:4]` by `[:]` when parsing idx, which failed because
      idx is 6 bytes length now.
- Extra: In node, use waitgroup instead of `stoppedXXX` channels to wait for
syncrhonizer goroutines to finish.

- Add ZKInputs parser to JSON
- Update ProcessTxs to last go-merkletree version changes
- Add StateDB test to generate ZKInputs to check inside a circom circuit
- Small fix at Til CoordinatorTx.LoadAmount=0

- Update StateDB ProcessTxs fees collection
- Update ProcessTxs tests to last StateDB & Til changes
- Til Blockchain L2Txs remove Nonce generation, update tests accordingly
- Update Til Set to test fees

- In Synchronizer test, test all tx types

Add TxTypeTransferToEthAddr&ToBJJ to StateDB & Til
resolves #203, resolves #209

In statedb:
- Store all values using prefixes for keys to allow iteration
- Add methods MTGetRoot, GetAccounts

Implement debugapi, an http server with debugging endpoints:
- debugAPI.GET("sdb/batchnum", a.handleCurrentBatch)
- debugAPI.GET("sdb/mtroot", a.handleMTRoot)
- debugAPI.GET("sdb/accounts", a.handleAccounts)
- debugAPI.GET("sdb/accounts/:Idx", a.handleAccount)

Transakcio:
- Transaction generation to fail when Transfer to an account that don't exist (not created yet)
- Add CreateAccountDepositCoordinator instruction feature
- Updated lang.go instruction type parser approach for more simplicity of code
- Remove `*testing.T` from transactions generation methods, use `log.Fatal` instead

- Add TxSel Nonce sort
- Fix surplus from refactors
- StateDB reuse computation of ToIdx across Synchronizer, TxSelector,
BatchBuilder

Add transakcio set type definition, add set loading, move transakcio to
package, adapt branch to last master updates (fix compile due new common
types & git conflicts).
Update tests to pass the test, pending to adapt to new Transakcio
interface.

- Implement SlicePtrsToSlice and use it in all `meddler.QueryAll` sql db functions to always return []Foo instead of []*Foo

- Implement new TxID spec that distinguishes L1UserTx and L1CoordinatorTx
- Replace some type []*Foo by []Foo
- Fix HistoryDB & L2DB bug: in case of error, a rollback was applied and the returned error was nil
- Reorder inserts in historydb.NewHistoryDB() to follow foreign key dependencies
- Add initial synchronizer test with test.Client (for now, only tested l1UserTxs, blocks, addToken)
- Update L1UserTx event in test.Client

* WIP: rebase

* Make nullable fields use pointers

Add StateDB compute nonces on ProcessTx L2Tx, and update StateDB for
type TypeSynchronizer, TypeTxSelector, TypeBatchBuilder

Add TxID calculation & New{Layer}Tx Type

New{Layer}Tx methods that compute the `TxID` & `TxType` values from the
transaction values:
- NewL1Tx
- NewL2Tx
- NewPoolL2Tx

Add TxID Scanner & Valuer for database/sql

HistoryDB & L2DB & API packages tests will need to be addapted to the
TestTransaction generation once is done.

- GetL2TxSelection & GetL1L2TxSelection integrated with dbs
- Create L1CoordinatorTx of type CreateAccountDeposit when a L2
requires it (and the AccountCreationAuth exists)