MIDI playback used samples instead of usec.
MIDI capture used time-stamp from previous cycle.
buffer-size changes were not applied to MIDI port latency
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.
* allow to change buffersizes
* subscribe to buffersize & samplerate changes
* add support for half-duplex devices.
* aggregate Devices (not yet used) code from JACK2
* unify deprecated API wrappers
* properly keep track of MIDI ports
* disable MidiI/O during freewheeling
* various small fixes & cleanup