Output from parallel subprocesses is an ugly, many-headed beast.
Piping though hydra-print provides an NCurses interface to a dynamic
set output streams, displayed without interleaving. This is a
common problem, for example, with parallel compiles, or
data-processing scripts.
Specifically, this small library will split the screen when
parallelism occurs, and unsplit it when the parallelism is
finished (i.e. dynamically growing and losing "heads").
The io-streams library is used for all stream inputs.