Reverting std lib is in std:: namespace and using .h versions instead

tinyxml2.cpp

@@ -30,8 +30,6 @@ distribution.
 #   include <cstddef>
 #endif
 
-using namespace std;
-
 static const char LINE_FEED				= (char)0x0a;			// all line endings are normalized to LF
 static const char LF = LINE_FEED;
 static const char CARRIAGE_RETURN		= (char)0x0d;			// CR gets filtered out