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/script/script.h

@@ -498,7 +498,7 @@ public:
     bool GetOp(iterator& pc, opcodetype& opcodeRet)
     {
          const_iterator pc2 = pc;
-         bool fRet = GetOp2(pc2, opcodeRet, NULL);
+         bool fRet = GetOp2(pc2, opcodeRet, nullptr);
          pc = begin() + (pc2 - begin());
          return fRet;
     }
@@ -510,7 +510,7 @@ public:
 
     bool GetOp(const_iterator& pc, opcodetype& opcodeRet) const
     {
-        return GetOp2(pc, opcodeRet, NULL);
+        return GetOp2(pc, opcodeRet, nullptr);
     }
 
     bool GetOp2(const_iterator& pc, opcodetype& opcodeRet, std::vector<unsigned char>* pvchRet) const