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(result15->GetInputSet().size(), 1U);
        
        available_coins.Clear();
        add_coin(available_coins, *wallet, CENT * 1 / 10);
        add_coin(available_coins, *wallet, CENT * 2 / 10);
        add_coin(available_coins, *wallet, CENT * 3 / 10);
        add_coin(available_coins, *wallet, CENT * 4 / 10);
        add_coin(available_coins, *wallet, CENT * 5 / 10);
        
        
        const auto result16 = KnapsackSolver(KnapsackGroupOutputs(available_coins.All(), *wallet, filter_confirmed), CENT, CENT);
        BOOST_CHECK(result16);
        BOOST_CHECK_EQUAL(result16->GetSelectedValue(), CENT);
        
        add_coin(available_coins, *wallet, 1111*CENT);
        
        const auto result17 = KnapsackSolver(KnapsackGroupOutputs(available_coins.All(), *wallet, filter_confirmed), 1 * CENT, CENT);
        BOOST_CHECK(result17);
        BOOST_CHECK_EQUAL(result17->GetSelectedValue(), 1 * CENT); 
        
        add_coin(available_coins, *wallet, CENT * 6 / 10);
        add_coin(available_coins, *wallet, CENT * 7 / 10);
        
        const auto result18 = KnapsackSolver(KnapsackGroupOutputs(available_coins.All(), *wallet, filter_confirmed), 1 * CENT, CENT);
        BOOST_CHECK(result18);
        BOOST_CHECK_EQUAL(result18->GetSelectedValue(), 1 * CENT); 
        
        
        available_coins.Clear();
        for (int j = 0; j < 20; j++)