qt: Minor message updates

Used sending/receiving addresses -> Sending/receiving addresses
Previously requested payments -> Requested payments (idea from @cozz in #3521)

src/qt/bitcoingui.cpp

@@ -302,12 +302,12 @@ void BitcoinGUI::createActions(bool fIsTestnet)
     openRPCConsoleAction = new QAction(QIcon(":/icons/debugwindow"), tr("&Debug window"), this);
     openRPCConsoleAction->setStatusTip(tr("Open debugging and diagnostic console"));
 
-    usedSendingAddressesAction = new QAction(QIcon(":/icons/address-book"), tr("&Used sending addresses..."), this);
+    usedSendingAddressesAction = new QAction(QIcon(":/icons/address-book"), tr("&Sending addresses..."), this);
     usedSendingAddressesAction->setStatusTip(tr("Show the list of used sending addresses and labels"));
-    usedReceivingAddressesAction = new QAction(QIcon(":/icons/address-book"), tr("Used &receiving addresses..."), this);
+    usedReceivingAddressesAction = new QAction(QIcon(":/icons/address-book"), tr("&Receiving addresses..."), this);
     usedReceivingAddressesAction->setStatusTip(tr("Show the list of used receiving addresses and labels"));
 
-    openAction = new QAction(QApplication::style()->standardIcon(QStyle::SP_FileIcon), tr("Open URI..."), this);
+    openAction = new QAction(QApplication::style()->standardIcon(QStyle::SP_FileIcon), tr("Open &URI..."), this);
     openAction->setStatusTip(tr("Open a bitcoin: URI or payment request"));
 
     connect(quitAction, SIGNAL(triggered()), qApp, SLOT(quit()));

src/qt/forms/receivecoinsdialog.ui

@@ -202,7 +202,7 @@
          </font>
         </property>
         <property name="text">
-         <string>Previously requested payments</string>
+         <string>Requested payments</string>
         </property>
        </widget>
       </item>