Reduce frequency that gate raise / lower sounds are triggered

[kieranhj]

Suggested by IP

what are your thoughts on triggering gate noise only every odd or even rise frame? (ie. it would sound half as often) (The gate lowering sounds are only triggered on alternate frames, same could be done for rising) you might want to halve gate lowering again, too this is me thinking about the PC version, mainly on the apple ii the crackle of a simple bit flip is probably small enough that it's useful to have it sound every frame

[kieranhj]

Fixed in branch.

[kieranhj]

In master.