simplify eventNameLink

Following up on #520 (closed). eventNameLink will never be able to accept anything other than $activeSlave without a significant rework of Long Slave Description, and it's sort of deceiving to imply otherwise.

This commit simply replaces all instances of <<EventNameLink $activeSlave>> with <<EventNameLink>>, and removes the arg[0] from the widget and comments.

There are no other <<EventNameLink $... situations.

Edit: tested with this save:

workout.save