propagate delta stream annotation changes as events

[Gary Poster]

This is the simplest generic way of making these annotation changes available to other parts of the code. Alternatively, we could try and keep annotations up to date on each model object, and allow people to subscribe to changes there. That would be fine with me in theory, but Ben points out that we already store some bits of annotation data on the controller objects in the environment view, so simply announcing the delta changes and letting code react to it only as necessary and as appropriate is perhaps better.

Sharing service location data needs something like this.

[Gary Poster (gary)]

Not necessary given the annotation approach in the delta stream