PStreams 0.5.2 released

Files can be downloaded under the 0.5.x release on
http://sf.net/projects/pstreams/

Includes support for streambuf::in_avail() to tell whether input
is available without blocking.

It's now possible to tell whether a command failed to
execute, since is_open() will not return true unless the
command was executed successfully, this is only possible
when using the argv functions to open a pstream.