spawn() that returns a duplex stream and emits errors with stderr data on non-zero exit codes
npm install comandanteSpawn commands returning a duplex stream. Emit stderr when the command exits
with a non-zero code.

`` js`
var run = require('commandante');
run('git', [ 'log' ]).pipe(process.stdout);
in a git directory we get:
``
$ node example/log.js | head -n3
commit ae5045cce4980a87b7151cfe91bc5889951aae39
Author: James Halliday
Date: Tue Oct 2 09:08:18 2012 -0700
in a non-git directory we get:
`
events.js:66
throw arguments[1]; // Unhandled 'error' event
^
Error: non-zero exit code 128: fatal: Not a git repository (or any of the parent directories): .git
at ChildProcess.
at ChildProcess.EventEmitter.emit (events.js:91:17)
at maybeClose (child_process.js:634:16)
at Socket.ChildProcess.spawn.stdin (child_process.js:805:11)
at Socket.EventEmitter.emit (events.js:88:17)
at Socket._destroy.destroyed (net.js:358:10)
at process.startup.processNextTick.process._tickCallback (node.js:244:9)
`
` js`
var commandante = require('commandante')
Spawn a new process like require('child_process').spawn(), except the return
value is a duplex stream combining stdout and stdin.
If the process exits with a non-zero status, emit an 'error' event with the
stderr data and the code in an informative message.
With npm do:
````
npm install comandante
MIT