Add [hold key] function on retarder to reset it [POLL]

[abasstreppas]

As the title says, add the "hold key" function on retarder to reset it to non active. As it is now you have to hit the key several times until it's deactivated. It will be more effective especially for keyboard users and probably for others too. Of c the "step" reducing of retarder will still be available. I just ask for an addition