scripted-diff: Use the C++11 keyword nullptr to denote the pointer literal instead of the macro NULL

-BEGIN VERIFY SCRIPT-
sed -i 's/\<NULL\>/nullptr/g' src/*.cpp src/*.h src/*/*.cpp src/*/*.h src/qt/*/*.cpp src/qt/*/*.h src/wallet/*/*.cpp src/wallet/*/*.h src/support/allocators/*.h
sed -i 's/Prefer nullptr, otherwise SAFECOOKIE./Prefer NULL, otherwise SAFECOOKIE./g' src/torcontrol.cpp
sed -i 's/tor: Using nullptr authentication/tor: Using NULL authentication/g' src/torcontrol.cpp
sed -i 's/METHODS=nullptr/METHODS=NULL/g' src/test/torcontrol_tests.cpp src/torcontrol.cpp
sed -i 's/nullptr certificates/NULL certificates/g' src/qt/paymentserver.cpp
sed -i 's/"nullptr"/"NULL"/g' src/torcontrol.cpp src/test/torcontrol_tests.cpp
-END VERIFY SCRIPT-

src/qt/recentrequeststablemodel.cpp

@@ -123,7 +123,7 @@ void RecentRequestsTableModel::updateAmountColumnTitle()
 /** Gets title for amount column including current display unit if optionsModel reference available. */
 QString RecentRequestsTableModel::getAmountTitle()
 {
-    return (this->walletModel->getOptionsModel() != NULL) ? tr("Requested") + " ("+BitcoinUnits::name(this->walletModel->getOptionsModel()->getDisplayUnit()) + ")" : "";
+    return (this->walletModel->getOptionsModel() != nullptr) ? tr("Requested") + " ("+BitcoinUnits::name(this->walletModel->getOptionsModel()->getDisplayUnit()) + ")" : "";
 }
 
 QModelIndex RecentRequestsTableModel::index(int row, int column, const QModelIndex &parent) const