Negative zero wpm/lesson

[Lich-Corals]

When learning with a guided lesson, the learning rate for the individual key seems to be able to be -0.0unit/lesson or +0.0unit/lesson. The happiness is also red or green, fitting the sign of the number.

I guess it's probably a problem of determining the sign of the number before rounding the rate to zero.

This certainly isn't a critical issue, but it surely doesn't look good to have a -0.