Updated Image Processing shader and GUI: gamma color processing follows

HSV transform. new Shader assignment operator.

Shader.h

@@ -41,7 +41,6 @@ class Shader
 
 public:
     Shader();
-//    virtual ~Shader() {}
 
     // unique identifyer generated at instanciation
     inline int id () const { return id_; }
@@ -50,6 +49,8 @@ public:
     virtual void reset();
     virtual void accept(Visitor& v);
 
+    void operator = (const Shader &D );
+
     glm::mat4 projection;
     glm::mat4 modelview;
     glm::vec4 color;