Make it possible to read input from stdin.
Make it possible to read input from stdin.

Without this change I don't see a way to
unpack a multivolume archive without wasting
disk space for a temporary file.

jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase