Add ServerEnvironment::setNode()/removeNode() to allow setting nodes from the C++ side with proper script-defined initialization/destruction

src/environment.h

@@ -283,6 +283,10 @@ public:
 		Other stuff
 		-------------------------------------------
 	*/
+
+	// Script-aware node setters
+	bool setNode(v3s16 p, const MapNode &n);
+	bool removeNode(v3s16 p);
 	
 	// Find all active objects inside a radius around a point
 	std::set<u16> getObjectsInsideRadius(v3f pos, float radius);