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.

const CAmount exact_target{in_amt - fee * 2};
    BOOST_CHECK_EQUAL(0, GetSelectionWaste(selection, 0, exact_target));
    selection.clear();
    
    const CAmount new_change_cost{fee_diff * 2};
    add_coin(1 * COIN, 1, selection, fee, fee + fee_diff);
    add_coin(2 * COIN, 2, selection, fee, fee + fee_diff);
    BOOST_CHECK_EQUAL(0, GetSelectionWaste(selection, new_change_cost, target));
    selection.clear();
    
    const CAmount new_target{in_amt - fee * 2 - fee_diff * 2};
    add_coin(1 * COIN, 1, selection, fee, fee + fee_diff);
    add_coin(2 * COIN, 2, selection, fee, fee + fee_diff);
    BOOST_CHECK_EQUAL(0, GetSelectionWaste(selection,  0, new_target));
    selection.clear();
    
    const CAmount exact_target1{3 * COIN - 2 * fee};
    const CAmount target_waste1{-2 * fee_diff}; 
    add_coin(1 * COIN, 1, selection, fee, fee + fee_diff);
    add_coin(2 * COIN, 2, selection, fee, fee + fee_diff);
    BOOST_CHECK_EQUAL(target_waste1, GetSelectionWaste(selection,  0, exact_target1));
    selection.clear();
    
    const CAmount large_fee_diff{90};
    const CAmount target_waste2{-2 * large_fee_diff + change_cost}; 
    add_coin(1 * COIN, 1, selection, fee, fee + large_fee_diff);
    add_coin(2 * COIN, 2, selection, fee, fee + large_fee_diff);
    BOOST_CHECK_EQUAL(target_waste2, GetSelectionWaste(selection, change_cost, target));
}
BOOST_AUTO_TEST_CASE(effective_value_test)