[unity] Build compile error after commit 01b8c06 due to unguarded using UnityEditor.namespace. Closes #2222.

spine-unity/Assets/Spine/Runtime/spine-unity/Components/SkeletonMecanim.cs

@@ -28,8 +28,10 @@
  *****************************************************************************/
 
 using System.Collections.Generic;
-using UnityEditor.Animations;
 using UnityEngine;
+#if UNITY_EDITOR
+using UnityEditor.Animations;
+#endif
 
 namespace Spine.Unity {
 	[RequireComponent(typeof(Animator))]

spine-unity/Assets/Spine/Runtime/spine-unity/Components/SkeletonRenderer.cs

@@ -51,8 +51,10 @@
 #define SPINE_OPTIONAL_MATERIALOVERRIDE
 
 using System.Collections.Generic;
-using UnityEditor.SceneManagement;
 using UnityEngine;
+#if UNITY_EDITOR
+using UnityEditor.SceneManagement;
+#endif
 
 namespace Spine.Unity {
 	/// <summary>Base class of animated Spine skeleton components. This component manages and renders a skeleton.</summary>