adding time_io + switch to pragma once for datastream.hpp

include/fc/datastream.hpp

@@ -1,5 +1,4 @@
-#ifndef _FC_DATASTREAM_HPP_
+#pragma once
-#define _FC_DATASTREAM_HPP_
 #include <fc/utility.hpp>
 #include <fc/error_report.hpp>
 #include <string.h>
@@ -114,4 +113,3 @@ private:
 
 } // namespace fc
 
-#endif

include/fc/time_io.hpp

@@ -0,0 +1,18 @@
+#pragma once
+#include <fc/time_point.hpp>
+#include <fc/raw.hpp>
+
+namespace fc {
+  namespace raw {
+    template<typename Stream, typename T>
+    void unpack( Stream& s, fc::time_point& v ) {
+      int64_t micro;  
+      fc::raw::unpack(s, micro );
+      v = fc::time_point( fc::microseconds(micro);
+    }
+    template<typename Stream, typename T>
+    void pack( Stream& s, const fc::time_point& v ) {
+      fc::raw::pack( s, v.time_since_epoch().count() );
+    }
+  }
+}