Add append_array() method to Array class

(cherry picked from commit 9f23a94b8a)

core/array.cpp

@@ -117,6 +117,11 @@ void Array::push_back(const Variant &p_value) {
 	_p->array.push_back(p_value);
 }
 
+void Array::append_array(const Array &p_array) {
+
+	_p->array.append_array(p_array._p->array);
+}
+
 Error Array::resize(int p_new_size) {
 
 	return _p->array.resize(p_new_size);