Attributes are working
Add slightly dubious connection semantics to stream

This is in order to support:

* Streams that immediately emit an initial value upon subscription
* Composing operations onto the Streams without losing the initial
  value (inspired by publishValue et al in Rx)
* However, this forces `map` and other operations to be aware of
  Connectable Streams, so they can connect to the parent after they
  subscribe. TODO: Investigate how Rx composes ConnectableObservable
  and `map`.
Clean up connectable streams
More tweaks to connection and update htmlbars