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/block_structure.h b/internal/ceres/block_structure.h
index 656716e..dde8f67 100644
--- a/internal/ceres/block_structure.h
+++ b/internal/ceres/block_structure.h
@@ -71,20 +71,20 @@
 
 struct CompressedList {
   Block block;
-  vector<Cell> cells;
+  std::vector<Cell> cells;
 };
 
 typedef CompressedList CompressedRow;
 typedef CompressedList CompressedColumn;
 
 struct CompressedRowBlockStructure {
-  vector<Block> cols;
-  vector<CompressedRow> rows;
+  std::vector<Block> cols;
+  std::vector<CompressedRow> rows;
 };
 
 struct CompressedColumnBlockStructure {
-  vector<Block> rows;
-  vector<CompressedColumn> cols;
+  std::vector<Block> rows;
+  std::vector<CompressedColumn> cols;
 };
 
 }  // namespace internal