Trigger note release instead of abrupt cutoff on note-off events.
(Thanks to Krzysztof Foltman for the patch.)
Issue was reported to the forums  that bass drum kicks on TR808
created a clicking sound when used with a MIDI controller. In the
sampler, NOTE OFF events create an abrupt mute on the instrument,
which creates a high-frequency click. This patch instead triggers a
release on the instrument, respecting the mute group of the