turn off debounce/throttle with a negative wait time

[tlancina]

Not sure if this is the best way to do this, but it seemed like the least impact on the existing configuration.

Only weird thing is negative numbers have to be specified explicitly like --t=-1, as yargs parses -t -1 to mean true otherwise.

[sbleon]

I think this is effectively resolved (albeit with a different API of --debounce 0) in #90, which has been merged. This PR can probably be closed.