Minor fixes

As the opencv's build-bot did not want to compile this revision, I had
to do some changes. In particular,
1) Removed unsigned int vs int comparisons, that were treated as errors
2) Removed unused variables and functions
3) Removed functions without previous declaration
4) Fixed whitespaces

modules/optim/test/test_denoise_tvl1.cpp

@@ -48,7 +48,6 @@ TEST(Optim_denoise_tvl1, regression_basic){
 
     //cv::imshow("test", images[0]);
     cv::optim::denoise_TVL1(images, res);
-    printf("hello here!\n");
     //cv::imshow("denoised", res);
     //cv::waitKey();