Bring back the oft hand hotkey

[Frank_Stein]

Back years ago, it was setup where the middle mouse key worked where clicking it would use your non-active hand.

Later, it was changed to instead switch your active hand.

Personally, I miss this feature. Since then, WASD mode was introduced and E also made a hotkey for hand switching.

I propose having a round start toggle that changes the function of the middle mouse key from swapping hands to using the oft hand, while keeping E as the swap hand hotkey