Exported variables in extended script should follow godot natural inheritance order

[Ranoller]

Godot version:

5e837b3

OS/device including version:

Win7

Issue description:

An script that extends other script class doesn´t shows in inspector the exported properties in the godot natural inheritance order.

Ej:
Script class named full_enemy that extends a class namedbasic_enemy that extends a class enemy_object that extends kinematicBody2D has this property order in inspector:

• enemy_object
• basic_enemy
• full_enemy
• KinematicBody2D
• PhysicsBody2D
  -etc......

If we follow the order that godot naturally follow in inspector (Down in inheritance), the order should be:

• full_enemy
• basic_enemy
• enemy_object
• KinematicBody2D
• PhysicsBody2D
  -etc......

(And could be great to see the class difference in inspector in the same way that you can see the differences between Node-Node2D-CanvasItem etc....)