This is mostly a simple lexical search+replace but the absence of operator< for
std::weak_ptr<T> leads to some complications, particularly with Evoral::Sequence
and ExportPortChannel.
This is in preparation to move RoueUI::SoloMuteRelease
to libardour to reuse the implementation in various places.
This also prepares the solo logic for exclusive port-monitoring.
Paul Davis
Robin Gareus