Add Palladium (PLM) coin

Palladium, PalladiumTestnet and PalladiumRegtest, with parameters from
palladiumcore (address prefixes, RPC ports, genesis hashes). The daemon
version/index requirements of the Bitcoin class are disabled, as Palladium Core
is based on Bitcoin Core 0.19.

Tests: chain params, address -> hashX, and mainnet block/transaction fixtures
taken from a synced node. The altcoin transaction test skips the address check
for witness outputs, as bech32 is not supported by Coin.address_to_hashX.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

tests/test_transactions.py

@@ -101,6 +101,8 @@ def test_transaction_alts(transaction_details_altcoin):
             address = spk["addresses"][0]
         else:
             address = spk["address"]
+        if spk.get("type", "").startswith("witness_"):
+            continue  # bech32 addresses are not supported by Coin.address_to_hashX
         assert coin.address_to_hashX(address) == coin.hashX_from_script(tx_pks)
         if issubclass(coin, Namecoin):
             if "nameOp" not in spk or "name" not in spk["nameOp"]: