feat: add transaction batching module

feat: plugin sendCoins batching support
feat: batching processing on poller
feat: mock-wallet batching
fix: bitcoin tx batching
fix: transaction batching db table

lib/plugins/wallet/bitcoind/bitcoind.js

@@ -81,13 +81,18 @@ function sendCoins (account, tx, settings, operatorId, feeMultiplier) {
 
 function sendCoinsBatch (account, txs, cryptoCode) {
   return checkCryptoCode(cryptoCode)
+    .then(() => calculateFeeDiscount(feeMultiplier))
+    .then(newFee => fetch('settxfee', [newFee]))
     .then(() => {
       const txAddressAmountPairs = _.map(tx => [tx.address, tx.cryptoAtoms.shift(-unitScale).toFixed(8)], txs)
       return Promise.all([JSON.stringify(_.fromPairs(txAddressAmountPairs))])
     })
     .then(([obj]) => fetch('sendmany', ['', obj]))
-    .then(res => ({
-      txid: res.txid
+    .then((txId) => fetch('gettransaction', [txId]))
+    .then((res) => _.pick(['fee', 'txid'], res))
+    .then((pickedObj) => ({
+      fee: BN(pickedObj.fee).abs().shift(unitScale).round(),
+      txid: pickedObj.txid
     }))
     .catch(err => {
       if (err.code === -6) throw new E.InsufficientFundsError()
@@ -173,5 +178,6 @@ module.exports = {
   newFunding,
   cryptoNetwork,
   fetchRBF,
-  estimateFee
+  estimateFee,
+  sendCoinsBatch
 }