Enhancement - Path integration

- Implemented Path::operator (std::string) const, to provide an
  automatic cast to std::string for any Path, File or Directory.
- Made use of new cast in various code.
- Changed use of spaces in atoi () calls.
- Switched from std::string::data () to std::string::c_str () calls.

src/Path.cpp

@@ -65,6 +65,12 @@ Path& Path::operator= (const Path& other)
   return *this;
 }
 
+////////////////////////////////////////////////////////////////////////////////
+Path::operator std::string () const
+{
+  return data;
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 std::string Path::name () const
 {