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.

{
    size_t size{0};
    for (const auto& it : coins) {
        size += it.second.size();
    }
    return size;
}
std::vector<COutput> CoinsResult::All() const
{
    std::vector<COutput> all;
    all.reserve(coins.size());
    for (const auto& it : coins) {
        all.insert(all.end(), it.second.begin(), it.second.end());
    }
    return all;
}
void CoinsResult::Clear() {
    coins.clear();
}
void CoinsResult::Erase(const std::unordered_set<COutPoint, SaltedOutpointHasher>& coins_to_remove)