[feature request] tri-state switch

[solsticedhiver]

I am already using bootstrap-toggle, so I don't really want to use anyhting else to have that tri-state feature.

By tri-state, I mean, when the switch is at the center, it is not enabled,
Then if it is switched on the left, it is in the "left" state.
And if switched to the right, it is switched to the "right" state.