pstream.h:1798:TODO call exited() to check for exit and clean up? leave to user?
pstream.h:2349:TODO  document behaviour if buffer replaced.
test_pstreams.cc:12:TODO test rpstream more
test_pstreams.cc:13:TODO test whether error_ cleared after successful open().
test_pstreams.cc:14:TODO more tests for vector open()
test_pstreams.cc:585:TODO more testing of other members
