Don't include <iostream> and "using" declarations in header files

<iostream> sucks in expensive initialization of the standard streams
and isn't appropriate in a header file. Use <istream> and <ostream>
instead.

using declarations should never appear at global scope in a header
file; source files get to decide what they want to use in their
namespace.

simgear/structure/SGSmplhist.hxx

@@ -25,12 +25,10 @@ Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 #endif
 #define SampleHistogram_h 1
 
-#include <iostream>
+#include <ostream>
 #include <fstream>
 #include "SGSmplstat.hxx"
 
-using namespace std;
-
 extern const int SampleHistogramMinimum;
 extern const int SampleHistogramMaximum;
 
@@ -56,7 +54,7 @@ public:
 
   double bucketThreshold (int i);
   int inBucket (int i);
-  void printBuckets (ostream &);
+  void printBuckets (std::ostream &);
 
 };