Remove expired ports:
2018-03-31 math/abacus: Unmaintained and has a broken shared library
2018-03-31 audio/muse: Unmaintained upstream, crashes at runtime
2018-03-31 net/paris-traceroute: Legacy paris-traceroute is not supported anymore. Use net/scamper instead
2018-04-01 net-im/cjc: Depends on expired net-im/py-xmpp
2018-02-28 net-im/py-pyxmpp: Obsoleted in favor of PyXMPP2