Follow clang-tidy and clazy suggestions

variables non-POD should not be 'static' outside a class. Always use and init variables. Delete useless classes.

ImageProcessingShader.cpp

@@ -12,7 +12,7 @@ const char* ImageProcessingShader::filter_names[12] = { "None", "Blur", "Sharpen
 ImageProcessingShader::ImageProcessingShader(): Shader()
 {
     program_ = &imageProcessingShadingProgram;
-    reset();
+    ImageProcessingShader::reset();
 }
 
 void ImageProcessingShader::use()