Remove call to free in finalize method

In classes File and Win, don't call the free method from the finalize
method; free is a collective call for these objects, which seems a bad
idea to call from finalize (for instance, the free call could
block). Fixes #9.
Merge branch 'master' into mpi3
Remove calls to free in finalization methods

For scampi3 classes
Update classes to MPI3 API