Rebased, and fixed command line parsing

Create one log file for each slave subprocess. Redirect both
stdout and stderr to this file

opm/simulators/flow/Main.cpp

@@ -52,6 +52,10 @@
 #include <fcntl.h>  // for open()
 #include <unistd.h> // for dup2(), close()
 
+#include <iostream>
+#include <fcntl.h>  // for open()
+#include <unistd.h> // for dup2(), close()
+
 namespace Opm {
 
 Main::Main(int argc, char** argv, bool ownMPI)