added more compatibility helpers @0.1.0

 - Added `NAN_GETTER`, `NAN_SETTER`
 - Added `NanThrowError` with single Local<Value> argument
 - Added `NanNewBufferHandle` with single uint32_t argument
 - Added `NanHasInstance(Persistent<FunctionTemplate>&, Handle<Value>)`
 - Added `Local<Function> NanCallback#GetSetter()`
 - Added `NanCallback#Call(int, Local<Value>[])`
 - Deprecated `NanCallback#Run(int, Local<Value>[])` in favour of Call