[unity] Corrected incorrect using statement (leading to a compile error under some conditions), related to previous commit 75b9321. Added BoundingBoxFollowerGraphic component. [..] See #1770.

spine-unity/Assets/Spine/Editor/spine-unity/Editor/Components/BoundingBoxFollowerGraphicInspector.cs

@@ -33,7 +33,7 @@
 
 using UnityEngine;
 using UnityEditor;
-using Boo.Lang;
+using System.Collections.Generic;
 
 namespace Spine.Unity.Editor {
 	using Event = UnityEngine.Event;