message: Make sure zerocoinspend mint change leaves a fee in the tx
diff: @@ -3722,6 +3722,11 @@ bool CWallet::CreateZerocoinMintTransaction(const CAmount nValue, CMutableTransa
  //mint a coin with the closest denomination to what is being requested
  nFeeRet = txNew.vout.size() * Params().Zerocoin_MintFee();
  nValueRemaining = nValue - nMintingValue - (isZCSpendChange ? nFeeRet : 0);
  +
  + // if this is change of a zerocoinspend, then we can't mint all change, at least something must be given as a fee
  + if (isZCSpendChange && nValueRemaining <= 1 * COIN)
  + break;
  +
  libzerocoin::CoinDenomination denomination = libzerocoin::AmountToClosestDenomination(nValueRemaining, nValueRemaining);
  if (denomination == libzerocoin::ZQ_ERROR)
  break;
  @@ -3965,7 +3970,6 @@ bool CWallet::CreateZerocoinSpendTransaction(CAmount nValue, int nSecurityLevel,
  {
  LOCK2(cs_main, cs_wallet);
  {
  - LogPrintf("ZCPRINT %s after lock\n", __func__);
  txNew.vin.clear();
  txNew.vout.clear();
  @@ -3991,7 +3995,6 @@ bool CWallet::CreateZerocoinSpendTransaction(CAmount nValue, int nSecurityLevel,
  scriptZerocoinSpend = GetScriptForDestination(vchPubKey.GetID());
  }
  - LogPrintf("ZCPRINT %s before minting\n", __func__);
  //add change output if we are spending too much (only applies to spending multiple at once)
  if (nChange) {
  //mint change as zerocoins
  