Use more efficient data structure
Change name to Queue

Don't create prototype short-hand
explain why fill-count is used
Move explanations to queue.js

Check capacity bounds when resizing
Fix nits
Make tasks callables

Previously, tasks needed to be functions. Now they may be any object
that implements "call". This will open the possibility of enqueing a
reusable callable object instead of a closure.
Reviewed for style

Queue may wend its way into [Collections][]

[Collections]: https://github.com/montagejs/collections