Make recent wavedash changes a toggle#47

I main zetter and before this patch my wavedash was really consistent, and now I usually get jump instead of wavedash. Apparently I was using the shield buffer in order to wavedash. I’m finding it hard to play Zetterburn and I’m not sure I have the time to both unlearn the old timing and force in a new one. If the shield buffer was a toggle in the controls it could still be helpful for people with two shield buttons, while not changing the timing for people who have already learned it.