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 otherwise only caught later in the rt-thread after
scheduling a RealTimeOperation via AutomationControl::check_rt.
There is no need to schedule cross-thread events when the
value is not about to be changed.
This can greatly reduce the number of signals emitted by
restoring a slot, which improves performance and also prevents
the EventPool from filling up with useless events.
The master needs to be restored first, otherwise setting
the master value with be propagated. Furthermore the
actual value is saved at the time of VCA assignment.
Restoring the vaule needs to scale by the master-reduced value.