Manage listeners from the kernel

Have the kernel directly manage event listeners. Support namespaced event names.

The kernel will use a private namespace in `branch/collection-events` to send meta events into the application using names that won't conflict with any possible application event name. Additionally, the kernel will need to have direct knowledge of event listeners in order to replicate them correctly.

This is a predecessor to `branch/collection-events`, which uses the event mechanism for the kernel to deliver meta events into the application.

@eric79 , please review.

Interesting alternatives ... I actually don't think the first variant is that bad (since the spaces in the comment are commented out, they still read as one long block to me).