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/wallet.js

@@ -75,6 +75,24 @@ function sendCoins (settings, tx) {
     })
 }
 
+function sendCoinsBatch (settings, txs, cryptoCode) {
+  return fetchWallet(settings, cryptoCode)
+    .then(r => {
+      return r.wallet.sendCoinsBatch(r.account, txs, cryptoCode)
+        .then(res => {
+          mem.clear(module.exports.balance)
+          return res
+        })
+    })
+    .catch(err => {
+      if (err.name === INSUFFICIENT_FUNDS_NAME) {
+        throw httpError(INSUFFICIENT_FUNDS_NAME, INSUFFICIENT_FUNDS_CODE)
+      }
+
+      throw err
+    })
+}
+
 function newAddress (settings, info, tx) {
   const walletAddressPromise = fetchWallet(settings, info.cryptoCode)
     .then(r => r.wallet.newAddress(r.account, info, tx, settings, r.operatorId))
@@ -235,11 +253,13 @@ const balanceFiltered = mem(_balance, {
 module.exports = {
   balance,
   sendCoins,
+  sendCoinsBatch,
   newAddress,
   getStatus,
   isStrictAddress,
   sweep,
   isHd,
   newFunding,
-  cryptoNetwork
+  cryptoNetwork,
+  supportsBatching
 }