[Feature Request] Sudden death mode

[PappasBrent]

It would be nice if ttyper offered a "sudden death" mode for those wanting to focus on improving their typing accuracy.
If one were to make a mistake in sudden death mode, they would instantly start a new test (for an example, see TypeRacer's sudden death mode.).
Currently one can simulate this behavior by pressing escape and then r whenever they make a mistake, but this is not ideal since it requires two extra keystrokes for each failed test.
Ideally, a user should be able to start ttyper in sudden death mode by passing a flag, e.g.:

ttyper --sudden-death

[PappasBrent]

If this feature sounds desirable, feel free to assign me to it.
I'm wiling to work on this myself and submit a PR for review after making the change.