Make acquire subprocess output capture non-blocking

[DissectBot]

There is no default way to do this on both Windows & Linux.

The best solution is to have a thread do the reading and let that block. An example can be found here:

[http://eyalarubas.com/python-subproc-nonblock.html]

 

Another way to do it is to make the way the winpmem module does it the default, with intermediate files where stdout and stderr are stored. This circumvents the need to implement non-blocking pipes.