An implementation of promises (aka deferreds, etc.) based on Crockford's
Promise slide, with chaining (in at least two senses of the word!) and
parallelization.

http://developer.yahoo.com/yui/theater/video.php?v=crockonjs-3
(Sorry, slides have been taken off slideshare. If anyone has a link, LMK.)

Uses the module system from https://github.com/rhowardiv/silly-module

Calling Promise() returns a Promise. Here are the methods of a Promise:

- when(Function): Add function to be run if/when the Promise is fulfilled.
  Returns the Promise.

- fail(Function): Add function to be run if/when the Promise is smashed.
  Returns the Promise.

- fulfill(result): Set the state of the Promise to "fulfilled". All "when"
  functions will be called with the result. Returns the Promise.

- smash(result): Set the state of the Promise to "smashed". All "fail"
  functions will be called with the result. Returns the Promise.

- status(): Get the state of the Promise. Can be 'unresolved,' 'fulfilled' or
  'smashed.'

- then(Promise): Provide another Promise or function or array to chain after
  this Promise. See PromiseChain.then(). Returns the resulting PromiseChain.

- also(Promise): Provide another Promise or function to run in parallel with
  this Promise. See PromiseChain.also(). Returns the resulting PromiseChain.


Calling then() or also() on a Promise, or calling PromiseChain() returns a
PromiseChain. Here are the methods of a PromiseChain():

- then(Promise): Provide a function or Promise or array to add to the chain.
  Returns the PromiseChain. If a function is provided, it will be called with
  the result of the previous Promise in the chain. If it returns a Promise,
  the chain continues. If it returns a false-y value, the chain is smashed.
  If an array of Promises/functions is provided, they will all be
  fulfilled/called before moving to the next link. If all Promises in this
  link are fulfilled, the results are gathered into an array which is passed
  to the fulfillment/call of the next link.

- also(Promise): Provide a Promise or function to run in parallel with
  the current last links--same as providing an array to then(). Returns
  the PromiseChain.

- when(Function): Add function to be run if/when the PromiseChain is
  fulfilled. Returns the PromiseChain.

- fail(Function): Add function to be run if/when the PromiseChain is smashed.
  Returns the PromiseChain.

- status(): Get the state of the PromiseChain; see Promise.status().