Next big coding style update - this time all PlayHandle classes are
affected. Functions like done() and released() were renamed to
isFinished() and isReleased().
In order to provide smooth muting functionality (i.e. immediate proper
sound when unmuting) always render audio buffers for MIDI-based
instruments. This is more important than potentially reduced CPU usage
while muted.
Closes#69.
While regular instruments were excluded from processing when muted
this did not happen for InstrumentPlayHandle-based instruments. Muting
for exampling tracks with VSTi's inside did not decrease CPU usage.
Checking whether related InstrumentTrack is muted before calling
Instrument::play() fixes this issue.
Closes#2857426.
(cherry picked from commit 6940d19969)