Add `nodeName` to IDL definition in Readme.md
Add new event mechanism

- Fix ordering of handler-invocation;
- Add new feature that checks if a the event should still be
  emitted, such as when, in an `insert` handler, the node is
  removed.

Closes GH-11

Note that this addition only counts for “dual” events,
remove/insert and such. Whereas changing values on `changetext`,
and changing the following node in `changenext` still results in
several events.
Merge branch 'feature/event-cancelation'
Update changelog for 0.2.0-rc.4
0.2.0-rc.4