Remove all using directives for STL namespace and members

Made all STL usages explicit to be able automatically find all usages of
particular class or function.

modules/imgproc/src/deriv.cpp

@@ -100,7 +100,7 @@ static void getSobelKernels( OutputArray _kx, OutputArray _ky,
 
     if( _ksize % 2 == 0 || _ksize > 31 )
         CV_Error( CV_StsOutOfRange, "The kernel size must be odd and not larger than 31" );
-    vector<int> kerI(std::max(ksizeX, ksizeY) + 1);
+    std::vector<int> kerI(std::max(ksizeX, ksizeY) + 1);
 
     CV_Assert( dx >= 0 && dy >= 0 && dx+dy > 0 );