ZClassic is now sapling activated
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### Description

I tried to add the same sapling settings than ZCash in coins.json, but with the correct height.
		  "overwinterActivationHeight": 476969,
          "overwinterTxVersion": 3,
          "overwinterTxVersionGroupId": 63210096,
          "saplingActivationHeight": 476969,
          "saplingTxVersion": 4,
          "saplingTxVersionGroupId": 2301567109

### Steps to Reproduce

1. I start the pool

### Actual behavior

[2019-03-07 15:20:28.4358] [E] [zclassic2] Error during UpdateJob System.ArgumentException: Field 'fOverwintered' defined on type 'NBitcoin.Zcash.ZcashTransaction' is not a field on the target object which is of type 'NBitcoin.Transaction'.
   at System.Reflection.RtFieldInfo.CheckConsistency(Object target)
   at System.Reflection.RtFieldInfo.InternalSetValue(Object obj, Object value, BindingFlags invokeAttr, Binder binder, CultureInfo culture, StackCrawlMark& stackMark)
   at System.Reflection.RtFieldInfo.SetValue(Object obj, Object value, BindingFlags invokeAttr, Binder binder, CultureInfo culture)
   at Miningcore.Blockchain.Equihash.EquihashJob.CreateOutputTransaction() in /root/miningcore/src/Miningcore/Blockchain/Equihash/EquihashJob.cs:line 100
   at Miningcore.Blockchain.Equihash.EquihashJob.BuildCoinbase() in /root/miningcore/src/Miningcore/Blockchain/Equihash/EquihashJob.cs:line 158
   at Miningcore.Blockchain.Equihash.EquihashJob.Init(EquihashBlockTemplate blockTemplate, String jobId, PoolConfig poolConfig, ClusterConfig clusterConfig, IMasterClock clock, IDestination poolAddressDestination, Network network, EquihashSolver solver) in /root/miningcore/src/Miningcore/Blockchain/Equihash/EquihashJob.cs:line 399
   at Miningcore.Blockchain.Equihash.EquihashJobManager.UpdateJob(Boolean forceUpdate, String via, String json) in /root/miningcore/src/Miningcore/Blockchain/Equihash/EquihashJobManager.cs:line 149    at System.Reflection.RtFieldInfo.CheckConsistency(Object target)
   at System.Reflection.RtFieldInfo.InternalSetValue(Object obj, Object value, BindingFlags invokeAttr, Binder binder, CultureInfo culture, StackCrawlMark& stackMark)
   at System.Reflection.RtFieldInfo.SetValue(Object obj, Object value, BindingFlags invokeAttr, Binder binder, CultureInfo culture)
   at Miningcore.Blockchain.Equihash.EquihashJob.CreateOutputTransaction() in /root/miningcore/src/Miningcore/Blockchain/Equihash/EquihashJob.cs:line 100
   at Miningcore.Blockchain.Equihash.EquihashJob.BuildCoinbase() in /root/miningcore/src/Miningcore/Blockchain/Equihash/EquihashJob.cs:line 158
   at Miningcore.Blockchain.Equihash.EquihashJob.Init(EquihashBlockTemplate blockTemplate, String jobId, PoolConfig poolConfig, ClusterConfig clusterConfig, IMasterClock clock, IDestination poolAddressDestination, Network network, EquihashSolver solver) in /root/miningcore/src/Miningcore/Blockchain/Equihash/EquihashJob.cs:line 399
   at Miningcore.Blockchain.Equihash.EquihashJobManager.UpdateJob(Boolean forceUpdate, String via, String json) in /root/miningcore/src/Miningcore/Blockchain/Equihash/EquihashJobManager.cs:line 149

### Reproduces how often

Keeps looping

### Version

latest version with https://github.com/coinfoundry/miningcore/commit/ad60fff850dc7ffd1eebbaad708e06dabaac564c
 applied

### Additional Information

Any additional information, log, configuration or data that might be necessary to reproduce the issue.
