message: Reject minting zerocoin unless it is the minimum denom
diff: @@ -5391,7 +5391,7 @@ string CWallet::MintZerocoinFromOutPoint(CAmount nValue, CWalletTx& wtxNew, std:
  string CWallet::MintZerocoin(CAmount nValue, CWalletTx& wtxNew, vector<CDeterministicMint>& vDMints, bool fAllowBasecoin, const CCoinControl* coinControl)
  {
  // Check amount
  - if (nValue <= 0)
  + if (nValue < libzerocoin::ZerocoinDenominationToAmount(libzerocoin::CoinDenomination::ZQ_TEN))
  return _("Invalid amount");
  CAmount nValueRequired = nValue + Params().Zerocoin_MintFee();
  