Run NAN v1 to v2 upgrade script

- The upgrade steps are almost undocumented, but simplified by running a series of `sed` commands on the source files.
- The script was [originally suggested](nodejs/nan#376) in a github issue for NAN.
- One version has been [released as a gist](https://gist.github.com/thlorenz/7e9d8ad15566c99fd116).
- [A modified version](https://gist.github.com/joelpurra/a1129ca1336c14bfd51b1a7ad0f79171) which works better with `getdns-node` was used.
- This commit contains only automated fixes; the next commit contains manual fixes to some regexp misses.

src/GNConstants.cpp

@@ -32,14 +32,14 @@
 
 using namespace v8;
 
-static inline void SetConstant(const char* name, int value, Handle<Object> exports) {
-    exports->ForceSet(NanNew<String>(name), NanNew<Integer>(value), ReadOnly);
+static inline void SetConstant(const char* name, int value, Local<Object> exports) {
+    exports->ForceSet(Nan::New<String>(name).ToLocalChecked(), Nan::New<Integer>(value), ReadOnly);
 }
 
-void GNConstants::Init(Handle<Object> target) {
+void GNConstants::Init(Local<Object> target) {
 
-    Local<Object> exports = NanNew<Object>();
-    target->ForceSet(NanNew<String>("constants"), exports, ReadOnly);
+    Local<Object> exports = Nan::New<Object>();
+    target->ForceSet(Nan::New<String>("constants").ToLocalChecked(), exports, ReadOnly);
 
     SetConstant("RETURN_GOOD",GETDNS_RETURN_GOOD,exports);
     SetConstant("RETURN_GENERIC_ERROR",GETDNS_RETURN_GENERIC_ERROR,exports);

src/GNConstants.h

@@ -34,7 +34,7 @@
 class GNConstants {
 public:
     // Node module initializer
-    static void Init(v8::Handle<v8::Object> exports);
+    static void Init(v8::Local<v8::Object> exports);
 private:
     GNConstants() { }
     ~GNConstants() { }