Instrument Shortcuts Additions

Simply adds a few extra shortcuts to the instrument editor list

These are the extra shortcuts (and where you can find them):

Instrument Box:Navigation:Select previous sample

Instrument Box:Navigation:Select next sample

Instrument Box:Edit:Move sample up

Instrument Box:Edit:Move sample down

Instrument Box:Edit:Insert new sample

Instrument Box:Edit:Delete sample

Instrument Box:Edit:Rename sample

Instrument Box:Edit:Clear sample