Merge bitcoin-core/gui#251: Improve URI/file handling message

ef3e1d7 qt: Improve URI/file handling message (Hennadii Stepanov)

Pull request description:

  This PR:
  - fixes missing spaces after full stops
  - makes the translation context much bigger

  The latter is the main motivation for this PR, as I became a translator 🐅

  Screenshots:
  - master (a9d1b40)

  ![DeepinScreenshot_select-area_20210317211750](https://user-images.githubusercontent.com/32963518/111527570-bd776880-8768-11eb-9035-96bb08067e74.png)

  - this PR:

  ![Screenshot from 2021-03-17 21-13-36](https://user-images.githubusercontent.com/32963518/111527727-e7308f80-8768-11eb-95c7-e8b802bfed5f.png)

ACKs for top commit:
  jarolrod:
    ACK ef3e1d7

Tree-SHA512: 8fbd1e3731b75866356fae201b3129126001600ca0197e83c05825e8c5bbbcf0132d6a6b808d7a5cbfbdde75ed1865ecbb651c30017570abd7c5803eff2b9306

src/qt/paymentserver.cpp

@@ -239,8 +239,8 @@ void PaymentServer::handleURIOrFile(const QString& s)
                 if (!IsValidDestination(dest)) {
                     if (uri.hasQueryItem("r")) {  // payment request
                         Q_EMIT message(tr("URI handling"),
-                            tr("Cannot process payment request as BIP70 is no longer supported.")+
-                            tr("Due to discontinued support, you should request the merchant to provide you with a BIP21 compatible URI or use a wallet that does continue to support BIP70."),
+                            tr("Cannot process payment request as BIP70 is no longer supported.\n"
+                               "Due to discontinued support, you should request the merchant to provide you with a BIP21 compatible URI or use a wallet that does continue to support BIP70."),
                             CClientUIInterface::ICON_WARNING);
                     } else {
                         Q_EMIT message(tr("URI handling"), QString::fromStdString(error_msg),
@@ -262,8 +262,8 @@ void PaymentServer::handleURIOrFile(const QString& s)
     if (QFile::exists(s)) // payment request file
     {
         Q_EMIT message(tr("Payment request file handling"),
-            tr("Cannot process payment request as BIP70 is no longer supported.")+
-            tr("Due to discontinued support, you should request the merchant to provide you with a BIP21 compatible URI or use a wallet that does continue to support BIP70."),
+            tr("Cannot process payment request as BIP70 is no longer supported.\n"
+               "Due to discontinued support, you should request the merchant to provide you with a BIP21 compatible URI or use a wallet that does continue to support BIP70."),
             CClientUIInterface::ICON_WARNING);
     }
 }