While regtesting with [bitcoin-spock](https://github.com/msgilligan/bitcoin-spock) I noticed at some point the transaction creation via `sendtoaddress -> CreateTransaction()` fails, because the created transaction is larger than `MAX_STANDARD_TX_SIZE`.

During the process a lot of raw transactions are created, which have smallish outputs and when then using `sendtoaddress`, it appears to attempt to create a transaction that spends too many of those dust-ish outputs.

The transaction to create does not have many outputs, but it looks like it's caused by the coin selection, which selects too many inputs. Testing was done with a 0.9 branch, but on the first glimpse I believe this issue is as well be present in 0.10. If this is a known issue, and if there is already a guard against this behavior, I'd be happy about a hint.

Sorry in advance, I do not have a test script to reproduce this issue in an isolated manner. A potential fix would probably require to adjust the coin selection, so that it selects a combination of coins, which, in addition to the size of the rest of the transaction, is still smaller than the limit.

BOOST_CHECK_EQUAL(result10->GetInputSet().size(), 1U);
        add_coin(available_coins, *wallet,  5*CENT); 
        
        const auto result11 = KnapsackSolver(KnapsackGroupOutputs(available_coins.All(), *wallet, filter_confirmed), 16 * CENT, CENT);
        BOOST_CHECK(result11);
        BOOST_CHECK_EQUAL(result11->GetSelectedValue(), 18 * CENT); 
        BOOST_CHECK_EQUAL(result11->GetInputSet().size(), 3U);
        add_coin(available_coins, *wallet,  18*CENT); 
        
        const auto result12 = KnapsackSolver(KnapsackGroupOutputs(available_coins.All(), *wallet, filter_confirmed), 16 * CENT, CENT);
        BOOST_CHECK(result12);
        BOOST_CHECK_EQUAL(result12->GetSelectedValue(), 18 * CENT);  
        BOOST_CHECK_EQUAL(result12->GetInputSet().size(), 1U); 
        
        const auto result13 = KnapsackSolver(KnapsackGroupOutputs(available_coins.All(), *wallet, filter_confirmed), 11 * CENT, CENT);
        BOOST_CHECK(result13);
        BOOST_CHECK_EQUAL(result13->GetSelectedValue(), 11 * CENT);
        BOOST_CHECK_EQUAL(result13->GetInputSet().size(), 2U);
        
        add_coin(available_coins, *wallet,  1*COIN);
        add_coin(available_coins, *wallet,  2*COIN);
        add_coin(available_coins, *wallet,  3*COIN);
        add_coin(available_coins, *wallet,  4*COIN); 
        const auto result14 = KnapsackSolver(KnapsackGroupOutputs(available_coins.All(), *wallet, filter_confirmed), 95 * CENT, CENT);
        BOOST_CHECK(result14);
        BOOST_CHECK_EQUAL(result14->GetSelectedValue(), 1 * COIN);  
        BOOST_CHECK_EQUAL(result14->GetInputSet().size(), 1U);
        const auto result15 = KnapsackSolver(KnapsackGroupOutputs(available_coins.All(), *wallet, filter_confirmed), 195 * CENT, CENT);
        BOOST_CHECK(result15);
        BOOST_CHECK_EQUAL(result15->GetSelectedValue(), 2 * COIN);