Octave +/- In Drum Mode

[AtomicUniverse]

I use Battery4 for drum presets, which has up to 48 samples per kit, so I always need to weigh out which sounds I really need. I absolutely love how drum sequencer works in BeatStep Pro and this change can make it near perfect. 

[megamarkd]

This would quite useful even if it was only ever the selected octave that was active.