Adding UV texture coordinates to Surface and ImageShader.

ImageShader.h

@@ -16,7 +16,6 @@ class ImageShader : public Shader
 public:
 
     ImageShader();
-//    virtual ~ImageShader() {}
 
     void use() override;
     void reset() override;
@@ -27,6 +26,7 @@ public:
     uint mask;
     uint custom_textureindex;
     float stipple;
+    glm::vec4 uv;
 
     static const char* mask_names[11];
     static std::vector< uint > mask_presets;