[Wallet] Improve ReorderTransactions(..)
[Qt] Call checkBalanceChanged() periodically instead for every updated transaction
Add testnet DNS seed of Andreas Schildbach.

It runs sipas crawler, but rather than using its custom nameserver implementation it serves a generated zonefile via bind9. The zone always contains 25 IPv4 and 25 IPv6 peers. FWIW, the zone is secured using DNSSEC.
Merge pull request #4862

45a4baf Add testnet DNS seed of Andreas Schildbach. (Andreas Schildbach)
Merge pull request #4697

da2ede2 [Wallet] Improve ReorderTransactions(..) (Cozz Lovan)
Merge pull request #4712

80daee0 [Qt] Call checkBalanceChanged() periodically instead for every updated transaction (Cozz Lovan)