pstream.h:1604:TODO call exited() to check for exit and clean up? leave to user?
pstream.h:2153:TODO  document behaviour if buffer replaced.
test_pstreams.cc:11:TODO test rpstream more
test_pstreams.cc:12:TODO test whether error_ cleared after successful open().
test_pstreams.cc:13:TODO more tests for vector open()
test_pstreams.cc:577:TODO more testing of other members
