Deprecate KDE4 software, categories a-c.
The last upstream release supporting KDE4 was 10 months ago,
https://www.kde.org/announcements/announce-applications-17.08.3.php ,
and the kde@ team for FreeBSD has supported modern KDE (i.e. KDE
Frameworks, Plasma 5 and KDE Applications) for 4 months. Give a 4
month deprecation period to allow users to switch over.
Not marked deprecated: audio/kid3-kde4, that's not ours, and it
supports Qt5 and KF5 as well despite its name.