cleanup json extensions use of texcoord, add normal texture info

UnityGLTF/Assets/UnityGLTF/Runtime/Plugins/GLTFSerialization/Extensions/GLTFJsonExtensions.cs

@@ -99,7 +99,6 @@ public static TextureInfo DeserializeAsTexture(this JToken token, GLTFRoot root)
 				// Broken on il2cpp. Don't ship debug DLLs there.
 				System.Diagnostics.Debug.WriteLine("textureObject is " + textureObject.Type + " with a value of: " + textureObject[TextureInfo.INDEX].Type + " " + textureObject.ToString());
 #endif
-
 				int indexVal = textureObject[TextureInfo.INDEX].DeserializeAsInt();
 				textureInfo = new TextureInfo()
 				{
@@ -109,11 +108,33 @@ public static TextureInfo DeserializeAsTexture(this JToken token, GLTFRoot root)
 						Root = root
 					}
 				};
+				if (textureObject.ContainsKey(TextureInfo.TEXCOORD))
+				{
+					textureInfo.TexCoord = textureObject[TextureInfo.TEXCOORD].DeserializeAsInt();
+				}
 			}
 
 			return textureInfo;
 		}
 
+		public static NormalTextureInfo DeserializeAsNormalTexture(this JToken token, GLTFRoot root)
+		{
+			var tex = DeserializeAsTexture(token, root);
+			if (tex != null)
+			{
+				var normalTex = new NormalTextureInfo() { Index = tex.Index, TexCoord = tex.TexCoord };
+				JObject textureObject = token as JObject;
+				if (textureObject.ContainsKey(NormalTextureInfo.SCALE))
+				{
+					normalTex.Scale = textureObject[NormalTextureInfo.SCALE].DeserializeAsDouble();
+				}
+
+				return normalTex;
+			}
+
+			return null;
+		}
+
 		public static int DeserializeAsInt(this JToken token)
 		{
 			if (token != null)

UnityGLTF/Assets/UnityGLTF/Runtime/Scripts/SceneExporter/ExporterTextures.cs

@@ -3,9 +3,7 @@
 using System.IO;
 using GLTF.Schema;
 using UnityEngine;
-using UnityEngine.Experimental.Rendering;
 using UnityGLTF.Cache;
-using UnityGLTF.Extensions;
 using Object = UnityEngine.Object;
 using WrapMode = GLTF.Schema.WrapMode;