New port: net-im/corebird

Corebird is a native GTK3 Twitter client that provides features
such as Direct Messages (DMs), Tweet notifications.

WWW: http://corebird.baedert.org/

PR: 197530
Submitted by: Carlos Jacobo Puga Medina <cpm@fbsd.es>
Reviewed by: tijl, olivierd, thierry