Allow pre- and post-processing values

[Tigrov]

Allow processing events

• After read
• Before insert
• After insert
• Before update
• After update
• Before save (before insert or update)
• After save (after insert or update)
• Before delete
• After delete

Could be realized as a trait

[samdark]

It could be done in two ways:

1. Overriding methods as in Yii2. This is alright, but there will be conflicts when multiple traits are used.
2. Events is a better way since you can add multiple behaviors simultaneously and, also, can handle these outside of the AR itself.