gui: Add NAT-PMP network option

src/qt/forms/optionsdialog.ui

@@ -259,6 +259,16 @@
          </property>
         </widget>
        </item>
+       <item>
+        <widget class="QCheckBox" name="mapPortNatpmp">
+         <property name="toolTip">
+          <string>Automatically open the Bitcoin client port on the router. This only works when your router supports NAT-PMP and it is enabled. The external port could be random.</string>
+         </property>
+         <property name="text">
+          <string>Map port using NA&amp;T-PMP</string>
+         </property>
+        </widget>
+       </item>
        <item>
         <widget class="QCheckBox" name="allowIncoming">
          <property name="toolTip">

src/qt/optionsdialog.cpp

@@ -50,6 +50,9 @@ OptionsDialog::OptionsDialog(QWidget *parent, bool enableWallet) :
     /* Network elements init */
 #ifndef USE_UPNP
     ui->mapPortUpnp->setEnabled(false);
+#endif
+#ifndef USE_NATPMP
+    ui->mapPortNatpmp->setEnabled(false);
 #endif
     connect(this, &QDialog::accepted, [this](){
         QSettings settings;
@@ -219,6 +222,7 @@ void OptionsDialog::setMapper()
 
     /* Network */
     mapper->addMapping(ui->mapPortUpnp, OptionsModel::MapPortUPnP);
+    mapper->addMapping(ui->mapPortNatpmp, OptionsModel::MapPortNatpmp);
     mapper->addMapping(ui->allowIncoming, OptionsModel::Listen);
 
     mapper->addMapping(ui->connectSocks, OptionsModel::ProxyUse);