IPC::Open3::Simple aims at making it very easy to start a shell command,
eventually feed its stdin with some data, then retrieve its stdout and stderr
separately.

When you want to run a shell command and parse its stdout/stderr or feed its
stdin, you often end up using IPC::Run, IPC::Cmd or IPC::Open3 with your own
parsing code, and end up writing more code than you intended. IPC::Open3::Simple
is about removing this overhead and making IPC::Open3 easier to use.

IPC::Open3::Simple calls IPC::Open3 and redirects stdin, stdout and stderr to
some function references passed in argument to the constructor. It does a select
on the input/output filehandles returned by IPC::Open3 and dispatches their
content to and from those functions.