provide user variable to define display cutoff %

[kevinj2016]

Currently keyfreq produces a huge output, displaying key frequencies even for keys that display as 0.00% of the key press population being recorded.

But really, this is a lot more than I need, and I really don't know what anyone could rationally do (in a productive way) with a series of a dozen lines that say "0.00%" of total output. It seems to me that users are mostly interested in keys at 1% or above (pick the cutoff number that makes you happy).

I think it would be helpful (to reduce output quantity and hard-to-do-anything-with "0.00%" lines) if keyfreq provided a user settable option variable to define the cutoff point for the display (internally, the 0.00% key stats could still be maintained).

That way, in my .emacs file, I could say "(setq keyfreq-display-cutoff 1.0)" to tell keyfreq to only show lines above 1.0% in the population, and I would have a nicer, more relevant display to study. Thanks