Add boolean HaveWatchonly and signal NotifyWatchonlyChanged

src/wallet.cpp

@@ -153,6 +153,7 @@ bool CWallet::AddWatchOnly(const CScript &dest)
     if (!CCryptoKeyStore::AddWatchOnly(dest))
         return false;
     nTimeFirstKey = 1; // No birthday information for watch-only keys.
+    NotifyWatchonlyChanged(true);
     if (!fFileBacked)
         return true;
     return CWalletDB(strWalletFile).WriteWatchOnly(dest);