Various operations clear the history (e.g. cleanup). In that
case the GUI correctly had an empty Undo/Redo history, but the
file on disk was left in place.
Next session load restored the old, incorrect Undo/Redo history.
This type of MIDI port fetches all of its data from inside ::cycle_start(),
and delivers it to a FIFO connected to another thread (typically a
control surface).
Unlike regular MidiPorts, which will be read from inside a Session::process()
call, these ports will read their data once per AudioEngine::process() cycle.
They therefore cannot use MidiPort::get_midi_buffer() which scales and adjusts
event timestamps as if the data is being accessed from within Session::process().
It is still an open question whether or not AsyncMIDIPort::cycle_start() should
still scale event timestamps by speed. In some respects it seems more appropriate
to do so, and the reading thread (e.g. a control surface) doesn't care about
the "nframes" limit on timestamps that exists for calls within a Session::process()
tree. For now, leave the timestamps unscaled by speed.
When loading a session with muted tracks, those tracks were
not initially muted, but ardour only faded them out.
The same happened to sends, and also tracks with non unity fader:
an initial fade from unity to target gain was done.
Now this send and deliveries always fade-in (like default Amp does).
If the file has a timestamp, it should be set in the region during import.
This keeps the BWF timestamp from being lost and allows the region context
menu item "Move to original Position" to work.
It does not affect where the region will be positioned during import. That
still follows the import dialog menu selection (playhead, session start,
etc). It just maintains data that the user can decided to use if needed.
This change also allows files to be imported to the source list and then
later placed on the timeline in the correct timestamped position.
"Always use Tabstops for block-indent (the code must be
formatted correctly with "[TAB] = N spaces" for any value of N).
Use space only for alignment." - https://ardour.org/styleguide.html
