Fixes in shader names

com.unity.vfx-toolbox/Workbench/Editor/Tools/FlowMapPainter.cs

         public override void Initialize()
         {
             m_RenderTexture = RenderTexture.GetTemporary(PaintDataWidth, PaintDataHeight, 0, RenderTextureFormat.ARGB32, RenderTextureReadWrite.Linear);
-            m_Material = new Material(Shader.Find("VFXToolbox/ImageScripter/FlowMapPaint"));
+            m_Material = new Material(Shader.Find("Hidden/VFXToolbox/ImageScripter/FlowMapPaint"));
             if (PaintData != null)
             {
                 Texture2D temp = new Texture2D(PaintDataWidth, PaintDataHeight, TextureFormat.ARGB32, false, true);
                         m_PreviewRT = RenderTexture.GetTemporary(PaintDataWidth, PaintDataHeight, 0, RenderTextureFormat.ARGB32);
                     }
                     if (m_PreviewMaterial == null)
-                        m_PreviewMaterial = new Material(Shader.Find("VFXToolbox/ImageScripter/FlowMapPainter.DisplayFlow"));
+                        m_PreviewMaterial = new Material(Shader.Find("Hidden/VFXToolbox/ImageScripter/FlowMapPainter.DisplayFlow"));
 
                     m_PreviewMaterial.SetTexture("_MainTex", PreviewTexture);
                     m_PreviewMaterial.SetTexture("_FlowTex", m_RenderTexture);

com.unity.vfx-toolbox/Workbench/Editor/Tools/NoiseGenerator.cs

         public override void Initialize()
         {
             m_RenderTexture = RenderTexture.GetTemporary(Width, Height, 0, RenderTextureFormat.ARGB32, RenderTextureReadWrite.Linear);
-            m_Material = new Material(Shader.Find("VFXToolbox/ImageScripter/NoiseGen"));
+            m_Material = new Material(Shader.Find("Hidden/VFXToolbox/ImageScripter/NoiseGen"));
         }
 
         public override bool OnCanvasGUI(WorkbenchImageCanvas canvas)

com.unity.vfx-toolbox/Workbench/Editor/Tools/ProgressionMapGenerator.cs

         public override void Initialize()
         {
             m_RenderTexture = RenderTexture.GetTemporary(PaintDataWidth, PaintDataHeight, 0, RenderTextureFormat.ARGB32, RenderTextureReadWrite.Linear);
-            m_Material = new Material(Shader.Find("VFXToolbox/ImageScripter/FlowMapPaint"));
+            m_Material = new Material(Shader.Find("Hidden/VFXToolbox/ImageScripter/FlowMapPaint"));
             if (PaintData != null)
             {
                 Texture2D temp = new Texture2D(PaintDataWidth, PaintDataHeight, TextureFormat.ARGB32, false, true);
                             m_PreviewRT = RenderTexture.GetTemporary(PaintDataWidth, PaintDataHeight, 0, RenderTextureFormat.ARGB32);
                         }
                         if (m_PreviewMaterial == null)
-                            m_PreviewMaterial = new Material(Shader.Find("VFXToolbox/ImageScripter/FlowMapPainter.DisplayFlow"));
+                            m_PreviewMaterial = new Material(Shader.Find("Hidden/VFXToolbox/ImageScripter/FlowMapPainter.DisplayFlow"));
 
                         m_PreviewMaterial.SetTexture("_MainTex", BaseTexture);
                         m_PreviewMaterial.SetTexture("_FlowTex", m_RenderTexture);

com.unity.vfx-toolbox/Workbench/Editor/Tools/Shaders/FlowMapPainter.DisplayFlow.shader

-Shader "VFXToolbox/ImageScripter/FlowMapPainter.DisplayFlow"
+Shader "Hidden/VFXToolbox/ImageScripter/FlowMapPainter.DisplayFlow"
 {
 	Properties 
 	{

com.unity.vfx-toolbox/Workbench/Editor/Tools/Shaders/FlowMapPainter.shader

-Shader "VFXToolbox/ImageScripter/FlowMapPaint"
+Shader "Hidden/VFXToolbox/ImageScripter/FlowMapPaint"
 {
 	Properties 
 	{

com.unity.vfx-toolbox/Workbench/Editor/Tools/Shaders/NoiseGen.shader

-// Based on 3d Value noise (iQ https://www.shadertoy.com/view/4sfGzS)
-Shader "VFXToolbox/ImageScripter/NoiseGen"
+Shader "Hidden/VFXToolbox/ImageScripter/NoiseGen"
 {
 	Properties
 	{