Run utils/trim-trailing-whitespace.py on codebase

examples/tutorial/first.cc

@@ -26,7 +26,7 @@
 // n0 -------------- n1
 //    point-to-point
 //
- 
+
 using namespace ns3;
 
 NS_LOG_COMPONENT_DEFINE ("FirstScriptExample");
@@ -36,7 +36,7 @@ main (int argc, char *argv[])
 {
   CommandLine cmd (__FILE__);
   cmd.Parse (argc, argv);
-  
+
   Time::SetResolution (Time::NS);
   LogComponentEnable ("UdpEchoClientApplication", LOG_LEVEL_INFO);
   LogComponentEnable ("UdpEchoServerApplication", LOG_LEVEL_INFO);