Sync Mk with ports
Prune 3 obsolete ports

FreeBSD Ports maintainers have already deleted the following:
  audio/mpc
  devel/p5-MooseX-ChainedAccessors
  www/trac-gitplugin
Update devel/p5-Module-Build to version 0.4203
Tweak misc/help2man version 1.43.3_1
Import devel/py-setuptools version 1.1.7_1
Tweak www/py-twistedWeb version 13.2.0
Tweak devel/py-twistedCore version 13.2.0
Tweak net-mgmt/net-snmp version 5.7.2_3
Update devel/p5-Readonly to version 1.04
Tweak graphics/OpenEXR version 2.1.0_1
Tweak net-im/py-twistedWords version 13.2.0
Tweak security/py-twistedConch version 13.2.0
Tweak dns/py-twistedNames version 13.2.0
Update security/p5-IO-Socket-SSL to version 1.961
Update textproc/p5-XML-Compile to version 1.40
Tweak lang/ruby19 version 1.9.3.484,1
Tweak mail/py-twistedMail version 13.2.0
Update devel/icmake to version 7.21.00
Tweak devel/py-twistedRunner version 13.2.0
Update devel/py-robotframework to version 2.8.2