Merge pull request #43 from csmith/master

Tidy up CallbackManager very slightly.
Add some missing parameters to parser events.
Merge pull request #44 from greboid/master

Add some missing parameters to parser events.
Remove unused methods.

Remove "non-critical" callbacks - if callers want to ignore the
exception they can just try/catch it.

Make addCallbackType private, and remove the unused delCallbackType
method.