Currently ::roll() may actually be a ::no_roll() under some circumstances.
This can also happen during count-in:
transport_stopped () == transport_rolling()
and during latency-preroll:
Global session-transport speed != 0, some tracks already roll,
read data from disk and feed latent plugins.
but other non-latent tracks or busses don't roll and still have to
behave like the switch from no_roll() to roll() has not yet happened.
This changes the game WRT to monitoring as well, previously, Route:roll()
called Route::no_roll_unlocked () for conditions outlined above.
Now Track::no_roll_unlocked is called and in some cases wrongly clears
the buffers before the signal hits the disk-writer. (more work is needed
related to 61f8e53b)
On the upside this also fixes an issue with MidiTrack::no_roll not keeping
a lock while pushing data into the step-edit-ringbuffer.
This is also a step towards consolidating all entry points:
::roll(), ::no_roll(), ::silent_roll() in the Route class.
5fa9f8b399