The notification-row partial and the mention email's "see in center"
button built their /notifications/details/<id> links from the numeric
primary key, so mention, digest and reminder emails still linked to the
numeric URL on a semantic-identifier instance.
The split view already resolves the id through find_by_display_id, which
accepts both the numeric id and the semantic identifier, so handing it
the work package lets to_param render the display id. Also drops the
unused split_view_work_package_id helper, whose to_i wrongly suggested
the route only accepts a numeric id.
Klaus Zanders