Use $this->trigger() instead of Event::trigger() to make it possible to listen to events in Behaviors

[kristiansp]

Description

I make extensive use of Feed Me events, and decided to move them to a behavior, as is also suggested in the Yii 2.0 documentation.

The problem is that some events are not picked up, and I've narrowed it down to events that are triggered in this way:

Event::trigger(static::class, self::EVENT_AFTER_PARSE_FEED, $event);

(from /services/DataTypes.php)

If the event is triggered from the object itself (like other Feed Me events are), then the Behavior will pick it up, for instance like this:

$this->trigger(self::EVENT_AFTER_PARSE_FEED, $event);

I'm guessing the issue here is that since the Behavior is attached dynamically, it's not registered when the class is added statically (btw, self::class gives the same result).

Unless there's any specific reason to trigger events with Event::trigger() instead of $this->trigger(), I would suggest to change them everywhere, so that events can be handled in behaviors consistently.