Remove using namespace std;

For historical reasons we had a "using namespace std;" in port.h. This
is generally a bad idea. So removing it and along the way doing a bunch
of cpplint cleanup.

Change-Id: Ia125601a55ae62695e247fb0250df4c6f86c46c6
diff --git a/internal/ceres/covariance_impl.h b/internal/ceres/covariance_impl.h
index 135f4a1..f2defe8 100644
--- a/internal/ceres/covariance_impl.h
+++ b/internal/ceres/covariance_impl.h
@@ -52,7 +52,8 @@
   ~CovarianceImpl();
 
   bool Compute(
-      const vector<pair<const double*, const double*> >& covariance_blocks,
+      const std::vector<std::pair<const double*,
+                                  const double*> >& covariance_blocks,
       ProblemImpl* problem);
 
   bool GetCovarianceBlock(const double* parameter_block1,
@@ -60,7 +61,8 @@
                           double* covariance_block) const;
 
   bool ComputeCovarianceSparsity(
-      const vector<pair<const double*, const double*> >& covariance_blocks,
+      const std::vector<std::pair<const double*,
+                                  const double*> >& covariance_blocks,
       ProblemImpl* problem);
 
   bool ComputeCovarianceValues();
@@ -78,8 +80,8 @@
   Problem::EvaluateOptions evaluate_options_;
   bool is_computed_;
   bool is_valid_;
-  map<const double*, int> parameter_block_to_row_index_;
-  set<const double*> constant_parameter_blocks_;
+  std::map<const double*, int> parameter_block_to_row_index_;
+  std::set<const double*> constant_parameter_blocks_;
   scoped_ptr<CompressedRowSparseMatrix> covariance_matrix_;
 };