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.

expected_result.Clear();
    
    add_coin(3 * CENT, 3, expected_result);
    add_coin(2 * CENT, 2, expected_result);
    const auto result3 = SelectCoinsBnB(GroupCoins(utxo_pool), 5 * CENT, 0.5 * CENT);
    BOOST_CHECK(result3);
    BOOST_CHECK(EquivalentResult(expected_result, *result3));
    BOOST_CHECK_EQUAL(result3->GetSelectedValue(), 5 * CENT);
    expected_result.Clear();
    
    BOOST_CHECK(!SelectCoinsBnB(GroupCoins(utxo_pool), 11 * CENT, 0.5 * CENT));
    expected_result.Clear();
    
    add_coin(1 * CENT, 1, expected_result);
    const auto result4 = SelectCoinsBnB(GroupCoins(utxo_pool), 0.9 * CENT, 0.5 * CENT);
    BOOST_CHECK(result4);
    BOOST_CHECK_EQUAL(result4->GetSelectedValue(), 1 * CENT);
    BOOST_CHECK(EquivalentResult(expected_result, *result4));
    expected_result.Clear();
    
    BOOST_CHECK(!SelectCoinsBnB(GroupCoins(utxo_pool), 0.9 * CENT, 0));
    expected_result.Clear();
    
    add_coin(5 * CENT, 5, utxo_pool);
    add_coin(4 * CENT, 4, expected_result);
    add_coin(3 * CENT, 3, expected_result);
    add_coin(2 * CENT, 2, expected_result);
    add_coin(1 * CENT, 1, expected_result);
    const auto result5 = SelectCoinsBnB(GroupCoins(utxo_pool), 10 * CENT, 0.5 * CENT);
    BOOST_CHECK(result5);