IPC::ShellCmd comes from the nth time I've had to implement a select loop and
wanted appropriate sudo/su privilege magic, environment variables that are set
in the child, working directories set etc.

It aims to provide a reasonable interface for setting up command execution
environment (working directory, environment variables, stdin, stdout and stderr
redirection if necessary), but allowing for ssh and sudo and magicking in the
appropriate shell quoting.

It tries to be flexible about how you might want to capture output, exit status
and other such, but in such a way as it's hopefully easy to understand and make
it work.

Setup method calls are chain-able in a File::Find::Rule kind of a way.
