Auto-adjusted latency + shortcut inc/dec latency

The audio latency could be switched to some kind of automated logic.

So if Renoise hits a cpu overload (already implemented), the latency could be increased to the next higher available latency, without stopping the song playback. Also there could be an option to start with 8ms always on song load then, so a maximal/minimum latency threshold setting.

Also there could be two shortcuts for increasing/decreasing latency on-the-fly, also without stopping playback.

I always like to use the most low latency possible in each song project, and always switching the latency manually in the prefs seems a bit of an annoying workflow.