More visual script work

-Block switches to 2d/3d editor if editing visual script
-Added cast node in flow control
-Added ability to do RPC in visual script
-Comment nodes
-Fix bug with inverted cable in connecting backwards
-Copy and paste nodes, including from different scripts

modules/gdscript/gd_script.h

@@ -162,6 +162,8 @@ public:
 	Variant _new(const Variant** p_args,int p_argcount,Variant::CallError& r_error);
 	virtual bool can_instance() const;
 
+	virtual Ref<Script> get_base_script() const;
+
 	virtual StringName get_instance_base_type() const; // this may not work in all scripts, will return empty if so
 	virtual ScriptInstance* instance_create(Object *p_this);
 	virtual bool instance_has(const Object *p_this) const;