richMode/view: clean up
test/utils: more helpful assertion errors
richMode: standardize render times.

The View now sets a setImmediate whenever a keydown events occurs,
which ensures that renders occur at a predictable time; previously,
the View would set a setImmediate whenever a plugin decided it wanted
to render changes, which left some uncertainty as to the order of
events.

Additionally, events are now emitted for each Delta type; these events
are emitted before any changes to either the view or the DOM have taken
place.

The changes to how the view renders broke a few tests, specifically
those dealing with when paragraph/section operations throw. I’m not
sure how to test these anymore, so, for now, they are being skipped.
richMode/view: don’t emit unnecessary render events.

The render event should be for when Deltas were actually resolved,
and changes to the DOM made; the changes to the View introduced in
the previous commit caused the render event to be emitted after
every key press.
delta: remove Delta.reduce( )
richMode/view: don’t update identical paragraphs

When a paragraphUpdate delta contains a paragraph that is identical to
the one currently in the View, no action is taken.