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.

{
    CoinSet selection;
    const CAmount fee{100};
    const CAmount change_cost{125};
    const CAmount fee_diff{40};
    const CAmount in_amt{3 * COIN};
    const CAmount target{2 * COIN};
    const CAmount excess{in_amt - fee * 2 - target};
    
    add_coin(1 * COIN, 1, selection, fee, fee - fee_diff);
    add_coin(2 * COIN, 2, selection, fee, fee - fee_diff);
    const CAmount waste1 = GetSelectionWaste(selection, change_cost, target);
    BOOST_CHECK_EQUAL(fee_diff * 2 + change_cost, waste1);
    selection.clear();
    
    add_coin(1 * COIN, 1, selection, fee, fee - fee_diff);
    add_coin(2 * COIN, 2, selection, fee, fee - fee_diff);
    const CAmount waste_nochange1 = GetSelectionWaste(selection, 0, target);
    BOOST_CHECK_EQUAL(fee_diff * 2 + excess, waste_nochange1);
    selection.clear();
    
    add_coin(1 * COIN, 1, selection, fee, fee);
    add_coin(2 * COIN, 2, selection, fee, fee);
    BOOST_CHECK_EQUAL(change_cost, GetSelectionWaste(selection, change_cost, target));
    selection.clear();