Set multiplier for simulated keystrokes based on WPM

[TanGentleman]

This could be applied in a few different ways, but the first task would be to find a reasonable normalization.

The 60ms with 15s std deviation implementation can be converted reasonably into WPM metrics instead. A testing framework would be very helpful.

[TanGentleman]

After some testing:

The normalization with a 1x speed multiplier, 120ms mean delay, and 40ms std deviation is around the same WPM as my own.

I'll probably plot some of the data and make a client facing function to set the intended wpm.

[TanGentleman]

I'll continue getting better metrics and make the prediction more sophisticated, but this can be implemented pretty simply with a new method, like: Generate.set_wpm(120)