[unity] Make Skeleton Material preview 2D.

spine-unity/Assets/spine-unity/Modules/Shaders/Spine-Skeleton-Fill.shader

@@ -9,7 +9,7 @@ Shader "Spine/Skeleton Fill" {
 		[NoScaleOffset]_MainTex ("MainTex", 2D) = "white" {}
 	}
 	SubShader {
-		Tags { "IgnoreProjector"="True" "Queue"="Transparent" "RenderType"="Transparent" "PreviewType"="Plane" }
+		Tags { "Queue"="Transparent" "IgnoreProjector"="True" "RenderType"="Transparent" "PreviewType"="Plane" }
 		Blend One OneMinusSrcAlpha
 		Cull Off
 		ZWrite Off

spine-unity/Assets/spine-unity/Modules/Shaders/Spine-Skeleton-Tint.shader

@@ -13,7 +13,7 @@ Shader "Spine/Skeleton Tint" {
 	}
 
 	SubShader {
-		Tags { "Queue"="Transparent" "IgnoreProjector"="True" "RenderType"="Transparent" }
+		Tags { "Queue"="Transparent" "IgnoreProjector"="True" "RenderType"="Transparent" "PreviewType"="Plane" }
 
 		Fog { Mode Off }
 		Cull Off

spine-unity/Assets/spine-unity/Shaders/Spine-Skeleton.shader

@@ -5,7 +5,7 @@ Shader "Spine/Skeleton" {
 	}
 
 	SubShader {
-		Tags { "Queue"="Transparent" "IgnoreProjector"="True" "RenderType"="Transparent" }
+		Tags { "Queue"="Transparent" "IgnoreProjector"="True" "RenderType"="Transparent" "PreviewType"="Plane"}
 
 		Fog { Mode Off }
 		Cull Off