[AttachSprites] script for Unity for sprite attaching

How does it work:
- attach this Script to any Prefab generated via Spriter2Unity
- keep all textures for this entity in Resources folder and preserve
folder structure (if something was under head/sthn it should be under
*/Resources/head/sthn)
- run the game - your prefab should have all it’s sprites attached
- while runtime, copy object with attached sprites to project to create
a new prefab