Support modification tracking by supply an event api?
The limitations in Peewee are really the maximum possible. Anything more should be implemented in the database as triggers.
 I'm trying to integrate Whoosh with Peewee just as the way [Flask-WhooshAlchemy](https://github.com/gyllstromk/Flask-WhooshAlchemy) uses [Flask-SQLAlchemy](https://github.com/mitsuhiko/flask-sqlalchemy/) to implement the so-called real-time indexing by tracking **CUD** actions. Maybe this is not a feasible idea.
 Well, if you use the `post_save` and `post_delete` hooks, you should be fine. This will not catch bulk inserts, updates or deletes, however.
 Without catching bulk operations may lead to confusion. Perhaps as you said above,

> The limitations in Peewee are really the maximum possible. 

Peewee has very limited signal support in `playhouse.signals` currently. Does it have any plan to supply a variety of hooks or an event api that could support modification tracking in the future?
