Fix spacing in docs about logging.
Added linebreaks to channel docs + updated it to match most recent modifications.
Added docs about widgets and their lifecycle.
First trigger'ed event is also async in Backbone.trigger() patched version

* improved management of "this" (stop being paranoid)
* documented everything
PubSub now uses Backbone Events instead of our custom implementation.
Lazy loading images had DOM + event handler leaks in it, so we cut it off.
Replacing deprecated usage of @el with @view.$el
Notifications provided by Mozaic core now stay on proportional to the length of the text.