pstream.h:1551:TODO call exited() to check for exit and clean up? leave to user?
pstream.h:2097:TODO  document behaviour if buffer replaced.
test_pstreams.cc:23:TODO test rpstream more
test_pstreams.cc:24:TODO test whether error_ cleared after successful open().
test_pstreams.cc:25:TODO more tests for vector open()
test_pstreams.cc:553:TODO more testing of other members
