sliders with more than one handler. (feature request)

[mercuriete]

It would be nice that the sliders could have 2 or more values.

for example, i need for my application an slider with 2 values: one for the minimum of a given variable and the other for the maximum.

there are a react component called react-slider that does that https://cell303.github.io/react-slider/
but there are not too much developers in that project.

thank you in advance, you work is awesome. :)

[hai-cea]

Thanks @mercuriete - dupe of #779