Merge #11167: Full BIP173 (Bech32) support

8213838 [Qt] tolerate BIP173/bech32 addresses during input validation (Jonas Schnelli)
06eaca6 [RPC] Wallet: test importing of native witness scripts (NicolasDorier)
fd0041a Use BIP173 addresses in segwit.py test (Pieter Wuille)
e278f12 Support BIP173 in addwitnessaddress (Pieter Wuille)
c091b99 Implement BIP173 addresses and tests (Pieter Wuille)
bd355b8 Add regtest testing to base58_tests (Pieter Wuille)
6565c55 Convert base58_tests from type/payload to scriptPubKey comparison (Pieter Wuille)
8fd2267 Import Bech32 C++ reference code & tests (Pieter Wuille)
1e46ebd Implement {Encode,Decode}Destination without CBitcoinAddress (Pieter Wuille)

Pull request description:

  Builds on top of #11117.

  This adds support for:
  * Creating BIP173 addresses for testing (through `addwitnessaddress`, though by default it still produces P2SH versions)
  * Sending to BIP173 addresses (including non-v0 ones)
  * Analysing BIP173 addresses (through `validateaddress`)

  It includes a reformatted version of the [C++ Bech32 reference code](https://github.com/sipa/bech32/tree/master/ref/c%2B%2B) and an independent implementation of the address encoding/decoding logic (integrated with CTxDestination). All BIP173 test vectors are included.

  Not included (and intended for other PRs):
  * Full wallet support for SegWit (which would include automatically adding witness scripts to the wallet during automatic keypool topup, SegWit change outputs, ...) [see #11403]
  * Splitting base58.cpp and tests/base58_tests.cpp up into base58-specific code, and "address encoding"-code [see #11372]
  * Error locating in UI for BIP173 addresses.

Tree-SHA512: 238031185fd07f3ac873c586043970cc2db91bf7735c3c168cb33a3db39a7bda81d4891b649685bb17ef90dc63af0328e7705d8cd3e8dafd6c4d3c08fb230341

src/wallet/wallet.cpp

@@ -111,7 +111,26 @@ public:
             Process(script);
     }
 
-    void operator()(const CNoDestination &none) {}
+    void operator()(const WitnessV0ScriptHash& scriptID)
+    {
+        CScriptID id;
+        CRIPEMD160().Write(scriptID.begin(), 32).Finalize(id.begin());
+        CScript script;
+        if (keystore.GetCScript(id, script)) {
+            Process(script);
+        }
+    }
+
+    void operator()(const WitnessV0KeyHash& keyid)
+    {
+        CKeyID id(keyid);
+        if (keystore.HaveKey(id)) {
+            vKeys.push_back(id);
+        }
+    }
+
+    template<typename X>
+    void operator()(const X &none) {}
 };
 
 const CWalletTx* CWallet::GetWalletTx(const uint256& hash) const