The writer will need to know which cells are the active cells after
post-processing (because these are the cells there is stored results
for in the pressure and saturation arrays), and thus not only the
raw input grid (to get the COORD and ZCORN arrays which is not easily
detainable from the UnstructuredGrid), *and* the UnstructuredGrid
needs to be available.
The code is now allowed to use C++11, where shared_ptr is available
in the standard. To specify that the parser object must be present
for the output writer in its entire lifetime, we require to be passed
a shared_ptr. (This can be faked for local storage anyway).
Due to a glitch the order of the names was put incorrectly in the file,
even though the comment stressed that it was important it was right!
Hat tip: @bska
The return type of the path methods has changed in newer version of
Boost; by wrapping them with a new path object we can get a string
in a way that is compatible for both version 2 and 3.
Hat tip: @bska
