flock.ugen.triggerBuffer will allocate voices even when the speed is set to zero

[colinbdclark]

Currently, the implementation of flock.ugen.triggerBuffer will allocate a new buffer voice whenever its trigger input transitions to a high state. However, if—for whatever reason—a voice's speed is set to 0, it will still allocate the voice despite the fact that the voice will never make any sound and will never be deallocated (since it never reads to the end of its buffer).

The voice allocation logic should be changed to never allocate voices when the current speed is zero.