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/calib3d/src/polynom_solver.cpp

@@ -1,9 +1,8 @@
+#include "precomp.hpp"
+#include "polynom_solver.h"
+
 #include <math.h>
 #include <iostream>
-using namespace std;
-#include "precomp.hpp"
-
-#include "polynom_solver.h"
 
 int solve_deg2(double a, double b, double c, double & x1, double & x2)
 {