Support non-linear ranges

[etimberg]

Got this idea when playing with the custom-steps sample. Would be cool to support a logarithmic interpolation on the slider.

Implementation Ideas

1. Built in support for 'linear' and 'logarithmic' interpolation
2. Custom interpolation support via props

[tannerlinsley]

The scale used internally could easily be exposed. All it does is translate a value into a width percentage. :)

[etimberg]

Already working on it ;)

[tannerlinsley]

Nice!

[etimberg]

Done in #5