Don't wait for people being slightly late

[kneasle]

This is well defined provided the cutoff is less than one place. This would entail roughly the following:

• Add some kind of cutoff (in the range 0 <= x <= 1 for how many places out someone has to be in order to trigger the WaitForUser
• Any time someone is less late than this, the WaitForUserRhythm's cumulative delay counter should not be incremented. Otherwise, the WaitForUserRhythm functions exactly the same way (so setting the param to 0 will gain the current behaviour).