MultiCB

Simple way to aggregate multiple node-style callbacks

``js
var multicb = require('multicb')

// default usage

var done = multicb()
doAsync(done())
doAsync(done())
doAsync(done())
done(function(err, results) {
console.log(err) // => undefined
console.log(results) /* =>
[
[undefined, 'foo'],
[undefined, 'bar'],
[undefined, 'baz']
]
*/
})

// pluck argument

var done = multicb({ pluck: 1 })
doAsync(done())
doAsync(done())
doAsync(done())
done(function(err, results) {
console.log(err) // => undefined
console.log(results) /* =>
[
'foo',
'bar',
'baz'
]
*/
})

// spread argument

var done = multicb({ pluck: 1, spread: true })
doAsync(done())
doAsync(done())
doAsync(done())
done(function(err, a, b, c) {
console.log(err) // => undefined
console.log(a) // => 'foo'
console.log(b) // => 'bar'
console.log(c) // => 'baz'
})
``