wallet: suggest the use of sweep_unmixable when not_enough_outs_to_mix is thrown

src/simplewallet/simplewallet.cpp

@@ -397,6 +397,7 @@ namespace
       {
         writer << "\n" << tr("output amount") << " = " << print_money(outs_for_amount.first) << ", " << tr("found outputs to use") << " = " << outs_for_amount.second;
       }
+      writer << tr("Please use sweep_unmixable.");
     }
     catch (const tools::error::tx_not_constructed&)
       {

src/wallet/api/wallet.cpp

@@ -1198,6 +1198,7 @@ PendingTransaction *WalletImpl::createTransaction(const string &dst_addr, const
             for (const std::pair<uint64_t, uint64_t> outs_for_amount : e.scanty_outs()) {
                 writer << "\n" << tr("output amount") << " = " << print_money(outs_for_amount.first) << ", " << tr("found outputs to use") << " = " << outs_for_amount.second;
             }
+            writer << "\n" << tr("Please sweep unmixable outputs.");
             m_errorString = writer.str();
             m_status = Status_Error;
         } catch (const tools::error::tx_not_constructed&) {

src/wallet/wallet_rpc_server.cpp

@@ -2425,7 +2425,7 @@ namespace tools
     catch (const tools::error::not_enough_outs_to_mix& e)
     {
       er.code = WALLET_RPC_ERROR_CODE_NOT_ENOUGH_OUTS_TO_MIX;
-      er.message = e.what();
+      er.message = e.what() + std::string(" Please use sweep_dust.");
     }
     catch (const error::file_exists& e)
     {