Add fromEvent adapter for EventTarget/EventEmitter.  Unit tests still
needed.

New MulticastSource that creates iterable queues with a "shared" view
of items.  Auto-activates when first queue is created, and auto
disposes when all active queues are ended

Make time explicit. Every event is tagged with a time, and every
stream with a scheduler. Refactor time-based combinators to use tagged
time whenenver possible.

Fix Stream.prototype.zipWith. Remove Stream.prototype.on for now

Use stream.beget to preserve scheduler

Improve periodic: its events always have exactly the periodic time,
even if they are emitted at a slightly different real world time (ie,
when a real world clock is being used).  Remove unused scheduler
methods.

Move default scheduler to Stream
Workaround annoying backward-incompatible jshint change that complains about redefining Promise. Bump version
Start to add dispose() infrastructure, that propagates dispose
function forward, and uses end signal to execute it. Fan-in type
streams, like merge, zip, concat, etc. don't yet support disposing
their input streams, but will in an upcoming commit.

Several performance improvements for merge and zip.
Simplify Queue
Add create() unit tests, and fixes for MulticastSource
Add jsdoc and header comments
Improve dispose handling.  Allows stream filters (like take) to dispose their sources properly without having to request a next item
Add MulticastSource unit tests, fixes
Add fromEvent unit tests and fixes
Make reduce use new disposer approach
Remove commented out lines
Merge pull request #22 from cujojs/improve-time-handling-add-imperative-event-source

Make event time explicit, add imperative event adapter