Create missing directories when creating a file

This is done when creating files from pgs scripts using

• output writers (gnuplot or VTK)
• creating raw files

src/language/utils/OFStream.cpp

 #include <language/utils/OFStream.hpp>
 
+#include <utils/Filesystem.hpp>
 #include <utils/Messenger.hpp>
 
 OFStream::OFStream(const std::string& filename)
 {
   if (parallel::rank() == 0) {
+    createDirectoryIfNeeded(filename);
     m_fstream.open(filename);
     if (m_fstream.is_open()) {
       m_ostream = &m_fstream;