Feature Request: Ability to pass other data to function assigned to barColor

[trojanware]

While using a function as value for "barColor", I have come across people needing arbitrary data(apart from percentage) to decide the color of a bar.
We could add a property in the config, eg: "barColorArgs" which accepts an array of props from the chart config, which will be passed to the function(in addition to percentage).
I will be sending a pull request in a couple of days, will be glad to get some feedback on this.

[josezulu]

Maybe this helps: #170 (comment)