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(EquivalentResult(expected_result, *result5));
    BOOST_CHECK_EQUAL(result5->GetSelectedValue(), 10 * CENT);
    expected_result.Clear();
    
    
    add_coin(5 * CENT, 5, expected_result);
    add_coin(3 * CENT, 3, expected_result);
    add_coin(2 * CENT, 2, expected_result);
    const auto result6 = SelectCoinsBnB(GroupCoins(utxo_pool), 10 * CENT, 5000);
    BOOST_CHECK(result6);
    BOOST_CHECK_EQUAL(result6->GetSelectedValue(), 10 * CENT);
    
    
    
    BOOST_CHECK(!SelectCoinsBnB(GroupCoins(utxo_pool), 0.25 * CENT, 0.5 * CENT));
    expected_result.Clear();
    
    CAmount target = make_hard_case(17, utxo_pool);
    BOOST_CHECK(!SelectCoinsBnB(GroupCoins(utxo_pool), target, 1)); 
    target = make_hard_case(14, utxo_pool);
    const auto result7 = SelectCoinsBnB(GroupCoins(utxo_pool), target, 1); 
    BOOST_CHECK(result7);
    
    utxo_pool.clear();
    add_coin(7 * CENT, 7, expected_result);
    add_coin(7 * CENT, 7, expected_result);
    add_coin(7 * CENT, 7, expected_result);
    add_coin(7 * CENT, 7, expected_result);
    add_coin(2 * CENT, 7, expected_result);
    add_coin(7 * CENT, 7, utxo_pool);