Fix crash when selected automation-lane is removed

Fix crash when selected automation-lane is removed

When a plugin is deleted, automation-lanes of the given plugin
are removed, but previously a pointed to the deleted lane remained
in the selection.

This caused crashes later when the track selection is used. e.g.
during sensitize_the_right_region_actions()

Note that ~TimeAxisView() also emits CatchDeletion (this);
however "this" fails to be dynamic_cast<AutomationTimeAxisView*>
because that d'tor has already been completed.